Polish splash screen window from large to small activity.

The splash screen window will be cropped by letterbox controller when
transfer it from a large activity to smaller activity.
Another similar case can happen when app calls
Activity#setRequestedOrientation, which changes the activity's bounds
and modify the window's surface position.
By reuse the mAssociatedTask to reparent the splash screen window to
task, we can fix the splash screen window on task so it won't resize
from transfer starting window anymore, also skip crop or offset the
window if it is associated to task.
Also polish a case that starting window can suddenly gone if the launch
activity isn't visible when remove starting window, it should be
onScreen if the associated task is visible.

Bug: 292187844
Bug: 278931413
Test: launch test app, verify the splash screen won't resize anymore
during transfer across trampoline activities. Also verify splash screen
window won't resize when activity request orientation.

Change-Id: I2fc540191e4db5afa4eafdbc71ab29bd3570d2d4