Introduce new presentation policies for Connected Displays

This change introces several new policies to presentations in the
form of PresentationController#canPresent(), which is called both
when a new presentation is being added and when any WM hieararchy
Change we're interested in happens.

The policies we introduce:
- All displays can't present simultaneously.
- A display can't have multiple presentations.
- A presentation can't cover its own host task.
- A globally focused host task on a different display is needed
 to show a presentation on a non-presenting display.

Flag: com.android.window.flags.enable_presentation_for_connected_displays
Bug: 390481621
Bug: 393945496
Bug: 394504684
Bug: 395475549
Bug: 396552435
Test: atest WmTests:PresentationControllerTests
Change-Id: I1fde2165494896d7a3db7d5aef28fdd0d04b400d