ListDetailsView unfocus content on SelectedIndex changed.

[Rosuavio]

Fixes #4244 Also un-focuses content when SelectedIndex is changed.

Makes sure that the details of the list details view is get un-selected when the SelectedIndex is updated directly.

Note: This does not completely fix #3546, which would need to unfocus the details when the user clicks another item in the list. See #4222

PR Type

What kind of change does this PR introduce?

• Bugfix

What is the current behavior?

What is the new behavior?

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)
• Header has been added to all new source files (run build/UpdateHeaders.bat)
• Contains NO breaking changes

Other information

[ghost]

Thanks RosarioPulella 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 🙌

[michael-hawker]

Smoketest failure was just the transient failing to find the correct NuGet package one... Kicked it off again.

[XAML-Knight]

Unit tests passed, when ran via build script

[XAML-Knight]

When first running both of these unit tests, they both failed. After running each of them in the Visual Studio debugger, and having them fail, again, they finally did pass, after the next pass.

[Rosuavio]

@XAML-Knight @michael-hawker I updated the tests, they should run more constantly now.

[ghost]

Hello @michael-hawker!

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