Fix MasterBehavior to propagate correctly to FlyoutPage

[PureWeen]

Description of Change

• Reusing the FlyoutLayoutBehavior Property for MasterBehavior Property was the wrong approach since the types don't match. This creates a new bindable property specific to MasterDetailPage and then propagates that up to FlyoutPage
• Add copy of all MasterDetailPage tests to FlyoutPage
• Add ContentPropertyAttribute for Detail on the FlyoutPage type

Issues Resolved

• fixes [Bug] Xamarin.Forms 5 - MasterDetailPage 'Split' behaviour not working anymore #12490

API Changes

Added ContentPropertyAttribute to FlyoutPage

	[RenderWith(typeof(_FlyoutPageRenderer))]
	[ContentProperty("Detail")]
	public class FlyoutPage : Page, IFlyoutPageController, IElementConfiguration<FlyoutPage>
	{

Platforms Affected

• Core/XAML (all platforms)

Testing Procedure

• Test various permutations of setting MasterBehavior and make sure that the app reacts accordingly

PR Checklist

• Targets the correct branch
• Tests are passing (or failures are unrelated)