Add verification symbols test (#234)

Fixes #236

### Changes
- Run VSCode backed integration tests using the nightly Dafny language server
- Always use a mocked `vscode` in the existing tests in `src/test/suite/extension.test.ts`. Note the missing `@global: true` annotation was added in the proxyquire usage.
- Fix a bug that prevented verification management from working with unsaved files
- Fix a bug that broke the restart server feature

### Testing
- [WIP] Add a test for the `dafny.restartServer` command. I had to turn this test off because it causes the following test to fail. It triggers an issue described here: microsoft/vscode-languageserver-node#755
- Add a integration test for verification management

Author: keyboardDrummer

.vscode/launch.json

@@ -39,9 +39,11 @@
       "request": "launch",
       "runtimeExecutable": "${execPath}",
       "args": [
+        "--disable-extensions",
         "--extensionDevelopmentPath=${workspaceFolder}",
         "--extensionTestsPath=${workspaceFolder}/out/src/test/suite/index"
       ],
+      "env": { "dafnyIdeVersion": "latest nightly" },
       "outFiles": [
         "${workspaceFolder}/out/**/*.js",
         "${workspaceFolder}/dist/**/*.js"

dist/.gitkeep

@@ -287,13 +287,13 @@
     "eslint": "^7.32.0",
     "glob": "^7.1.7",
     "mocha": "^9.2.0",
-    "node-fetch": "^3.2.6",
     "ts-loader": "^9.2.5",
     "typescript": "^4.4.3",
     "webpack": "^5.52.1",
     "webpack-cli": "^4.10.0"
   },
   "dependencies": {
+    "cross-fetch": "^3.1.5",
     "extract-zip": "^2.0.1",
     "got": "^11.8.2",
     "promise.any": "^2.0.2",
@@ -302,4 +302,4 @@
     "vscode-uri": "^3.0.2",
     "which": "^2.0.2"
   }
-}
+}

package-lock.json

@@ -13,10 +13,7 @@ import { ConfigurationConstants, LanguageServerConstants } from '../constants';
 import Configuration from '../configuration';
 import { exec } from 'child_process';
 import { chdir as processChdir, cwd as processCwd } from 'process';
-import { RequestInfo, RequestInit } from 'node-fetch';
-
-const fetch = (url: RequestInfo, init?: RequestInit) =>
-  import('node-fetch').then(({ default: fetch }) => fetch(url, init));
+import fetch from 'cross-fetch';
 
 const execAsync = promisify(exec);
 
@@ -45,7 +42,7 @@ async function getConfiguredTagAndVersion(): Promise<[string, string]> {
 }
 
 async function getConfiguredGitTagAndVersionUncached(): Promise<[string, string]> {
-  let version = Configuration.get<string>(ConfigurationConstants.PreferredVersion);
+  let version = process.env['dafnyIdeVersion'] ?? Configuration.get<string>(ConfigurationConstants.PreferredVersion);
   switch(version) {
   case LanguageServerConstants.LatestStable:
     version = LanguageServerConstants.LatestVersion;