Task level letterboxing for cold start with ignore orientation request

1. Return false for handlesOrientationChangeFromDescendant() when
ignoring orientation request, so Task will be letterboxed on cold start.
2. When Task is letterboxed, CompatDisplayInsets should use the Task
size instead.
3. ShellTaskOrganizer places FULLSCREEN Task to (0,0), which doesn't
work well with task level letterboxing.

Bug: 170725334
Bug: 155431879
Test: atest WmTests:SizeCompatTests
Test: manual: adb shell wm set-ignore-orientation-request true
Change-Id: Ifdc30fd5e52df5db11bef80d1a124e017ce146b6