Add XAML Behaviors Skill

[michael-hawker]

Now with @marcelwgn's #14 merged, we should add additional skills for other libraries.

I'll add one for XAML Behaviors as a common defacto XAML pattern.

Reference docs:

• https://github.com/microsoft/XamlBehaviors/wiki (needs to be updated for 3.0)
• https://learn.microsoft.com/en-us/dotnet/communitytoolkit/windows/behaviors/
• https://xamlbrewer.wordpress.com/2023/01/16/xaml-behaviors-and-winui-3/

Should also call out the pitfalls ChangePropertyAction and EventTriggerBehavior with AOT, see: microsoft/XamlBehaviors#309 (at least until this PR gets merged).