[RESTRICT AUTOMERGE] WCT#setReparentLeafTaskIfRelaunch

This CL allows disassociating the leaf task if relaunched and
reparented it to TDA as root task for split-screen.

Bug: 236317871
Test: atest WindowOrganizerTests

Change-Id: I6704fab733ed7d239d7004c93d3d2f471ac94822
Merged-In: I6704fab733ed7d239d7004c93d3d2f471ac94822
5 files changed