feat(typespec): bump to 0.56.0 (#4708)

* feat(typespec): bump to 0.56.0

- bump typespec and corresponding libraries to the level of version 0.56.0
- fix unit test case due to deprecated operation template
- update anonymous return model definition to align with a breaking change

resolve #4699

* fix code gen mismatch

* fix test error

---------

Co-authored-by: Mingzhe Huang (from Dev Box) <mingzhehuang@microsoft.com>

package.json

@@ -4,7 +4,7 @@
   "description": "package.json intended for in-repo use only, package.json used for publishing is located in src/AutoRest.CSharp/package.json",
   "devDependencies": {
     "@azure-tools/cadl-ranch-mockapis": "file:test/CadlRanchMockApis",
-    "@azure-tools/typespec-client-generator-core": "0.41.8",
+    "@azure-tools/typespec-client-generator-core": "0.42.2",
     "@azure-tools/typespec-csharp": "file:src/TypeSpec.Extension/Emitter.Csharp",
     "@azure-tools/unbranded-tests": "file:test/UnbrandedProjects",
     "@microsoft.azure/autorest.testserver": "3.3.48",