added support of C#11 to templates

[vlada-shubina]

Problem

In the templates, the generators which determine minimum language version in use were not considering C#11.
Fixed regex to support it.

Customer impact

Without this fix, using C# 11.0 via --langVersion option will result in old style template (no top level statements, file scoped namespaces, implicit usings)

Testing

Automated

Risk

Very low.
Language version option is only available in CLI and not exposed in Visual Studio.

Microsoft Reviewers: Open in CodeFlow

[vlada-shubina]

@merriemcgaw @RussKie please help to review and ensure it gets to 7.0, thank you.

do you have any automation tests to cover this change?

cc: @baronfel

[baronfel]

The SDK version of this same fix was just approved for merge, so this should be merge-able as well for 7.0: dotnet/sdk#27361

[dreddy-work]

The SDK version of this same fix was just approved for merge, so this should be merge-able as well for 7.0: dotnet/sdk#27361

@baronfel , I missed part of the discussion in tactics. Is that sdk branch pointing RC1 or RC2?

[baronfel]

It's on the 'base' 7.0.1xx branch, which right now is RC2.

[dreddy-work]

/backport to main

[github-actions]

Started backporting to main: https://github.com/dotnet/winforms/actions/runs/2913582126

[RussKie]

do you have any automation tests to cover this change?

Unfortunately we don't. Still waiting for dotnet/templating#3868 ;)