Rename MDP to Flyoutpage

[PureWeen]

Description of Change

Rename MDP to Flyoutpage

• fixes [Spec] Major Breaking Changes Proposed for Xamarin.Forms 5.0 #11857

API Changes

Added:

	public class FlyoutPage
	{
		Page Flyout,
                Page Detail
	}

	public enum FlyoutLayoutBehavior
	{
		Default = 0,
		SplitOnLandscape = 1,
		Split = 2,
		Popover = 3,
		SplitOnPortrait = 4
	}

Platforms Affected

• Core/XAML (all platforms)
• iOS
• Android
• UWP

Behavioral/Visual Changes

None

Before/After Screenshots

Not applicable

Testing Procedure

PR Checklist

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

[jsuarezruiz]

The build is failing in the Tizen project "'IMasterDetailPageController' is obsolete: 'FLYOUTPAGE'".

[jsuarezruiz]

There are pending changes mostly in the issues project. What will happen to all the tests where TestMasterDetailPage is used? Will be changed to use FlyoutPage?

[PureWeen]

@jsuarezruiz eventually yes but I wanted to keep the CG setup for MDP so the UI tests can validate that it still works

[rmarinho]

Failing tests not related

[Tommigun1980]

This change broke the NuGets in my project, #12224, so I had to revert back to Xamarin.Forms 4 as it may take months for plugins to get updated, in case they ever will.