Update @azure-tools/typespec-client-generator-core to 0.56.2 and @typespec/http-client-csharp to latest version (#5334)

* Initial plan for issue

* Update package versions in package.json files

Co-authored-by: ArcturusZhang <[email protected]>

* Run npm install to update package-lock.json

Co-authored-by: ArcturusZhang <[email protected]>

* Update progress with note about connectivity issues

Co-authored-by: ArcturusZhang <[email protected]>

* regen

* Revert executable permission on eng/Generate.ps1

Co-authored-by: ArcturusZhang <[email protected]>

* fix the discriminator example issue

* changed that part to return null which is the best we could do

* fix generation issues

---------

Co-authored-by: copilot-swe-agent[bot] <[email protected]>
Co-authored-by: ArcturusZhang <[email protected]>
Co-authored-by: Dapeng Zhang <[email protected]>

Author: Copilot

package-lock.json

@@ -16,7 +16,7 @@
     "@typespec/spector": "0.1.0-alpha.14",
     "@azure-tools/azure-http-specs": "0.1.0-alpha.17",
     "@azure-tools/typespec-azure-resource-manager": "0.56.2",
-    "@azure-tools/typespec-client-generator-core": "0.56.0",
+    "@azure-tools/typespec-client-generator-core": "0.56.2",
     "@azure-tools/typespec-csharp": "file:src/TypeSpec.Extension/Emitter.Csharp",
     "@azure-tools/unbranded-tests": "file:test/UnbrandedProjects",
     "@microsoft.azure/autorest.testserver": "3.3.50",