Adjusted uwp project files to match WCT.

[shweaver-MSFT]

Also updated some broken tests after provider event name change, and a bug in the LoginButton.

PR Type

What kind of change does this PR introduce?

• Bugfix

What is the current behavior?

WCT uses a special csproj format for UWP projects, and the Graph-Controls repo should match.

Here is an example from WCT:
https://github.com/windows-toolkit/WindowsCommunityToolkit/blob/main/Microsoft.Toolkit.Uwp.UI.Controls.Input/Microsoft.Toolkit.Uwp.UI.Controls.Input.csproj

What is the new behavior?

The csproj formats in the following packages now match the way WCT handles UWP projects:

1. CommunityToolkit.Authentication.Uwp
2. CommunityToolkit.Graph.Uwp

PR Checklist

Please check if your PR fulfills the following requirements:

• Tested code with current supported SDKs
• 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
• Tests for the changes have been added (for bug fixes / features) (if applicable)
• Header has been added to all new source files (run build/UpdateHeaders.bat)
• Contains NO breaking changes

Other information

[ghost]

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