Add ActivityEmbeddingLaunchTests#testSecondaryActivityLaunchAbove

Creates a test that verifies if an activity is launched
from the secondary activity that only the primary
activity can be split with, then the newly launched
activity launches above the current secondary activity
in the same container.

Visually:
Stage of Test | Primary Container | Secondary Container
--------------|-------------------|--------------------
Start         |          A        |          B
--------------|-------------------|--------------------
B launches C  |          A        |          C
              |                   |          B
--------------|-------------------|--------------------

Bug: b/202748345
Test: atest CtsWindowManagerJetpackTestCases:ActivityEmbeddingLaunchTests#testSecondaryActivityLaunchAbove
Change-Id: I9235a411d26f139c87249906832d9da7d5d8f657
2 files changed