App Handle education UI

UI for app handle education. WindowingEducationViewController.kt controls the lifecycle of an education tooltip, including showing and hiding it. Ensures that only one tooltip is displayed at a time.
This CL as it is does not populate any UI. In follow up CL I will intergrate WindowingEducationViewController with AppHandleEducationController to inflate CL at valid triggers.

Fixes: 365053639
Fixes: 365054640
Fixes: 365926474
Test: atest DesktopWindowingEducationTooltipControllerTest
Flag: com.android.window.flags.enable_desktop_windowing_app_handle_education
Change-Id: I2cfdb56d0c5ae5b71807954a485637209c5ba89f