Initial implementation of LaunchingBoundsController.

This changelist introduces the LaunchingBoundsController, a central
location for calculating launch bounds. It also defines a
positioner interface that can be registered with LaunchingBoundsController
to participate in bounds calculation.

Test: bit FrameworksServicesTests:com.android.server.am.LaunchingTaskPositionerTests
Test: bit FrameworksServicesTests:com.android.server.am.LaunchingActivityPositionerTests
Test: bit FrameworksServicesTests:com.android.server.am.LaunchingBoundsControllerTests
Bug: 64144308
Change-Id: I35eaf095e2edd562375403413050ce82618c44f2