fix(@angular-devkit/schematics): hide install output by default

Current output:
```
kamik@RED-X1C6 MINGW64 /d/sandbox/latest-app (master)
$ ng update @angular/cli --next --force
Using package manager: 'yarn'
Collecting installed dependencies...
Found 30 dependencies.
Fetching dependency metadata from registry...
                  Package "@angular-devkit/build-angular" has a missing peer dependency of "@angular/localize" @ "^9.0.0-next.11".
    Updating package.json with dependency @angular/cli @ "9.0.0-next.15" (was "9.0.0-next.14")...
    Updating package.json with dependency @angular-devkit/build-angular @ "0.900.0-next.15" (was "0.900.0-next.14")...
    Updating package.json with dependency typescript @ "3.6.4" (was "3.5.3")...
UPDATE package.json (1353 bytes)
warning @angular-devkit/[email protected]: The engine "pnpm" appears to be invalid.
warning @angular-devkit/[email protected]: The engine "pnpm" appears to be invalid.
warning @ngtools/[email protected]: The engine "pnpm" appears to be invalid.
warning @angular-devkit/[email protected]: The engine "pnpm" appears to be invalid.
warning @angular-devkit/[email protected]: The engine "pnpm" appears to be invalid.
warning @angular-devkit/[email protected]: The engine "pnpm" appears to be invalid.
warning @angular/[email protected]: The engine "pnpm" appears to be invalid.
warning @schematics/[email protected]: The engine "pnpm" appears to be invalid.
warning @angular-devkit/[email protected]: The engine "pnpm" appears to be invalid.
warning @schematics/[email protected]: The engine "pnpm" appears to be invalid.
Compiling @angular/animations : es2015 as esm2015
Compiling @angular/compiler/testing : es2015 as esm2015
Compiling @angular/core : es2015 as esm2015
Compiling @angular/common : es2015 as esm2015
Compiling @angular/animations/browser : es2015 as esm2015
Compiling @angular/animations/browser/testing : es2015 as esm2015
Compiling @angular/core/testing : es2015 as esm2015
Compiling @angular/platform-browser : es2015 as esm2015
Compiling @angular/common/testing : es2015 as esm2015
Compiling @angular/platform-browser/testing : es2015 as esm2015
Compiling @angular/platform-browser/animations : es2015 as esm2015
Compiling @angular/common/http : es2015 as esm2015
Compiling @angular/router : es2015 as esm2015
Compiling @angular/forms : es2015 as esm2015
Compiling @angular/platform-browser-dynamic : es2015 as esm2015
Compiling @angular/common/http/testing : es2015 as esm2015
Compiling @angular/router/testing : es2015 as esm2015
Compiling @angular/platform-browser-dynamic/testing : es2015 as esm2015
```

New success output:
```
kamik@RED-X1C6 MINGW64 /d/sandbox/latest-app (master)
$ ng update @angular/cli --next --force
Using package manager: 'yarn'
Collecting installed dependencies...
Found 30 dependencies.
Fetching dependency metadata from registry...
                  Package "@angular-devkit/build-angular" has a missing peer dependency of "@angular/localize" @ "^9.0.0-next.11".
    Updating package.json with dependency @angular/cli @ "9.0.0-next.15" (was "9.0.0-next.14")...
    Updating package.json with dependency @angular-devkit/build-angular @ "0.900.0-next.15" (was "0.900.0-next.14")...
    Updating package.json with dependency typescript @ "3.6.4" (was "3.5.3")...
UPDATE package.json (1353 bytes)
Installing packages...
Packages installed successfully.
```

New error output:
```
kamik@RED-X1C6 MINGW64 /d/sandbox/latest-app (master)
$ ng update @angular/cli --next --force
Using package manager: 'yarn'
Collecting installed dependencies...
Found 30 dependencies.
Fetching dependency metadata from registry...
                  Package "@angular-devkit/build-angular" has a missing peer dependency of "@angular/localize" @ "^9.0.0-next.11".
    Updating package.json with dependency @angular/cli @ "9.0.0-next.15" (was "9.0.0-next.14")...
    Updating package.json with dependency @angular-devkit/build-angular @ "0.900.0-next.15" (was "0.900.0-next.14")...
    Updating package.json with dependency typescript @ "3.6.4" (was "3.5.3")...
UPDATE package.json (1353 bytes)
Installing packages...
warning @angular-devkit/[email protected]: The engine "pnpm" appears to be invalid.
warning @angular-devkit/[email protected]: The engine "pnpm" appears to be invalid.
warning @angular-devkit/[email protected]: The engine "pnpm" appears to be invalid.
warning @ngtools/[email protected]: The engine "pnpm" appears to be invalid.
warning @angular-devkit/[email protected]: The engine "pnpm" appears to be invalid.
warning @angular-devkit/[email protected]: The engine "pnpm" appears to be invalid.
warning @angular/[email protected]: The engine "pnpm" appears to be invalid.
warning @schematics/[email protected]: The engine "pnpm" appears to be invalid.
warning @angular-devkit/[email protected]: The engine "pnpm" appears to be invalid.
warning @schematics/[email protected]: The engine "pnpm" appears to be invalid.
Compiling @angular/animations : es2015 as esm2015
Compiling @angular/compiler/testing : es2015 as esm2015
Compiling @angular/core : es2015 as esm2015
Compiling @angular/common : es2015 as esm2015
Compiling @angular/animations/browser : es2015 as esm2015
Compiling @angular/animations/browser/testing : es2015 as esm2015
Compiling @angular/core/testing : es2015 as esm2015
Compiling @angular/platform-browser : es2015 as esm2015
Compiling @angular/common/testing : es2015 as esm2015
Compiling @angular/platform-browser/testing : es2015 as esm2015
Compiling @angular/platform-browser/animations : es2015 as esm2015
Compiling @angular/common/http : es2015 as esm2015
Compiling @angular/forms : es2015 as esm2015
Compiling @angular/router : es2015 as esm2015
Compiling @angular/platform-browser-dynamic : es2015 as esm2015
Compiling @angular/common/http/testing : es2015 as esm2015
Compiling @angular/platform-browser-dynamic/testing : es2015 as esm2015
Compiling @angular/router/testing : es2015 as esm2015
Package install failed, see above.
```

Author: filipesilva

etc/api/angular_devkit/schematics/tasks/index.d.ts

@@ -1,4 +1,5 @@
 export declare class NodePackageInstallTask implements TaskConfigurationGenerator<NodePackageTaskOptions> {
+    hideOutput: boolean;
     packageManager?: string;
     packageName?: string;
     quiet: boolean;

packages/angular_devkit/schematics/tasks/node-package/executor.ts

@@ -77,10 +77,9 @@ export default function(
       taskPackageManagerName = options.packageManager;
     }
 
-    const outputStream = process.stdout;
-    const errorStream = process.stderr;
+    const bufferedOutput: {stream: NodeJS.WriteStream, data: Buffer}[] = [];
     const spawnOptions: SpawnOptions = {
-      stdio:  [ process.stdin, outputStream, errorStream ],
+      stdio: !!options.hideOutput ? 'pipe' : 'inherit',
       shell: true,
       cwd: path.join(rootDirectory, options.workingDirectory || ''),
     };
@@ -100,16 +99,29 @@ export default function(
     }
 
     return new Observable(obs => {
-      spawn(taskPackageManagerName, args, spawnOptions)
+      // tslint:disable-next-line: no-console
+      console.log('Installing packages...');
+      const childProcess = spawn(taskPackageManagerName, args, spawnOptions)
         .on('close', (code: number) => {
           if (code === 0) {
+            // tslint:disable-next-line: no-console
+            console.log('Packages installed successfully.');
             obs.next();
             obs.complete();
           } else {
+            if (options.hideOutput) {
+              bufferedOutput.forEach(({ stream, data }) => stream.write(data));
+            }
             const message = 'Package install failed, see above.';
             obs.error(new Error(message));
           }
       });
+      if (options.hideOutput) {
+        childProcess.stdout.on('data', (data: Buffer) =>
+          bufferedOutput.push({ stream: process.stdout, data: data }));
+        childProcess.stderr.on('data', (data: Buffer) =>
+          bufferedOutput.push({ stream: process.stderr, data: data }));
+      }
     });
 
   };

packages/angular_devkit/schematics/tasks/node-package/install-task.ts

@@ -13,10 +13,12 @@ export class NodePackageInstallTaskOptions {
   packageName: string;
   workingDirectory: string;
   quiet: boolean;
+  hideOutput: boolean;
 }
 
 export class NodePackageInstallTask implements TaskConfigurationGenerator<NodePackageTaskOptions> {
   quiet = true;
+  hideOutput = true;
   workingDirectory?: string;
   packageManager?: string;
   packageName?: string;
@@ -30,6 +32,9 @@ export class NodePackageInstallTask implements TaskConfigurationGenerator<NodePa
       if (options.quiet != undefined) {
         this.quiet = options.quiet;
       }
+      if (options.hideOutput != undefined) {
+        this.hideOutput = options.hideOutput;
+      }
       if (options.workingDirectory != undefined) {
         this.workingDirectory = options.workingDirectory;
       }
@@ -48,6 +53,7 @@ export class NodePackageInstallTask implements TaskConfigurationGenerator<NodePa
       options: {
         command: 'install',
         quiet: this.quiet,
+        hideOutput: this.hideOutput,
         workingDirectory: this.workingDirectory,
         packageManager: this.packageManager,
         packageName: this.packageName,

packages/angular_devkit/schematics/tasks/node-package/options.ts

@@ -16,6 +16,7 @@ export interface NodePackageTaskFactoryOptions {
 export interface NodePackageTaskOptions {
   command: string;
   quiet?: boolean;
+  hideOutput?: boolean;
   workingDirectory?: string;
   packageName?: string;
   packageManager?: string;