Add coverage for parameterized Generate Method

[davidwengier]

Summary

• add GenerateMethodTests coverage for method invocations with parameters inside @code
• add matching implicit-expression coverage to confirm the parameterized Roslyn path is exercised

Testing

• dotnet test src\Razor\test\Microsoft.VisualStudio.LanguageServices.Razor.Test\Microsoft.VisualStudio.LanguageServices.Razor.Test.csproj --filter "FullyQualifiedName~GenerateMethod"
• dotnet test src\Razor\test\Microsoft.VisualStudioCode.RazorExtension.Test\Microsoft.VisualStudioCode.RazorExtension.Test.csproj --filter "FullyQualifiedName~GenerateMethod"

[davidwengier]

When I looked at Roslyn I thought "Generate Parameterized Method" was a separate code action that would have to be allow-listed, but its reported as just a plain Generate Method action, so it was already working. Just needed some test coverage.

[davidwengier]

Without the Roslyn insertion that preceeded this PR, these tests won't run, but it's still worth adding, so have updated them to be skipped. We can unskip all of the generate method tests at once post repo merge.