[Flicker] Add test for entering PIP with source rect hint

Adds flicker test for the CUJ with entering pip with source rect hint.
This specifically tests with auto enter enabled, but we can probably
add a separate case for entering manually. The test uses a rectangle
as the source rect, and there is a jump at the end of the transition
as the app doesn't update the layout for pip, but this is more of an
app issue and doesn't affect the test case.

Flags: N/A
Bug: 284200208
Test: atest EnterPipWithSourceRectHintTest
Change-Id: I47ab50f19dc421dc0e0262c7b14f5b37dfb3551e