Enable XYFocus behavior

[kikisaints]

Xbox needs the ability to specify where focus should go when using the gamepad. Today, in XAML, this is done through setting the XYFocus properties on a UIElement. A similar behavior is needed in RNWCPP (or one that yields the same run time result).

[kmelmon]

can maybe get info from Matt Haggert on how this was done for Playstation

[jonthysell]

Looking here for documentation: https://docs.microsoft.com/en-us/windows/uwp/design/input/gamepad-and-remote-interactions#xy-focus-navigation-and-interaction

Looks like we need to expose the XYFocus properties to Views, where you specify a specific element when a direction is pressed, but we'll need to provide some kind of identifier (tag?) to the target View:

P1:

• Control.XYFocusUp
• Control.XYFocusDown
• Control.XYFocusLeft
• Control.XYFocusRight

Do we need to expose the XYFocusNavigationStrategy-based properties? If so, I think they'd be P2.

P2:

• UIElement.XYFocusUpNavigationStrategy
• UIElement.XYFocusDownNavigationStrategy
• UIElement.XYFocusLeftNavigationStrategy
• UIElement.XYFocusRightNavigationStrategy

[jonthysell]

Currently verifying if we need this for Milestone 2.