Customizable exit splash screen animation.(2/N)

Introduce new APIs to customize exit splash screen animation.
- SplashScreen
  This can be used for Activity to handle the exit splash screen
  animation.
- SplashScreen#OnExitAnimationListener
  When receive onSplashScreenExit, the splash screen view will be on
  top of the activity.
- SplashScreenView
  The view object which represents the view of current starting window.
  There are two APIs for developer to control it:
  - getIconView: get the icon view object.
  - remove: remove the view and release resources.

If an Activity create a OnExitAnimationListener and set on
SplashScreen, the core will request a copy of SplashScreenView
from Shell, then send the parcelable information to client to
reconstruct the view on top of the DecorView, then call
onSplashScreenExit to let the listener able to operating this view.

Bug: 73289295
Test: build/flash, check splash screen starting window.
Test: atest StartingSurfaceDrawerTests ActivityRecordTests
WindowOrganizerTests
Test: atest CtsWindowManagerDeviceTestCases:SplashscreenTests

Change-Id: I9f77fb4471bcf37a7f74d6c18a345ca56c05b716