.NET Standard extraction

[XAML-Knight]

The .NET Standard Code has been moved to a new repo, and is no longer meant to be maintained by the Windows Community Toolkit repo. This PR is the removal of said .NET Standard code from the Toolkit.

Fixes #4382

PR Type

What kind of change does this PR introduce?

• Refactoring (no functional changes, no api changes)

What is the current behavior?

The Community Toolkit contains .NET Standard code

What is the new behavior?

.NET Standard code is removed from the toolkit. Specifically, it's these projects and associated unit tests that are being removed:

• Microsoft.Toolkit
• Microsoft.Toolkit.Diagnostics
• Microsoft.Toolkit.HighPerformance
• Microsoft.Toolkit.Mvvm
• Microsoft.Toolkit.Mvvm.SourceGenerators

Code that previously depended on the Microsoft.Toolkit code was updated to instead grab from the Microsoft.Toolkit.* NuGet packages.

PR Checklist

Please check if your PR fulfills the following requirements:

• Tested code with current supported SDKs
• New component
  • Pull Request has been submitted to the documentation repository instructions. Link:
  • Added description of major feature to project description for NuGet package (4000 total character limit, so don't push entire description over that)
  • If control, added to Visual Studio Design project
• Sample in sample app has been added / updated (for bug fixes / features)
  • Icon has been created (if new sample) following the Thumbnail Style Guide and templates
• New major technical changes in the toolkit have or will be added to the Wiki e.g. build changes, source generators, testing infrastructure, sample creation changes, etc...
• Tests for the changes have been added (for bug fixes / features) (if applicable)
  • Tests which were duplicating those appearing in the dotnet repo have been removed
• Header has been added to all new source files (run build/UpdateHeaders.bat)
• Contains NO breaking changes

Other information

[ghost]

Thanks XAML-Knight for opening a Pull Request! The reviewers will test the PR and highlight if there is any conflict or changes required. If the PR is approved we will proceed to merge the pull request 🙌

[Sergio0694]

The deleted code seems ok, but there's a few things to resolve still.
Also you forgot to delete the .NET solution filter file 🙂

[ghost]

This PR has been marked as "needs attention 👋" and awaiting a response from the team.

[Sergio0694]

Looks much better, we're almost there! 😄
Remember to also delete the solution filter!

[ghost]

This PR has been marked as "needs attention 👋" and awaiting a response from the team.

[XAML-Knight]

... Remember to also delete the solution filter!

Deleted

[michael-hawker]

LGTM @Sergio0694?

[Sergio0694]

@michael-hawker Was planning on taking a look tomorrow morning just to double check again 😄
Happy to take care of merging it then if you want.

[Sergio0694]

LGTM!

@michael-hawker Feel free to squash-merge this and/or to decide how to proceed with respect to other PRs.
The changes here are good on their own, so good to go for me 👍