Do not ignore home activity focus change on multi TaskDisplayArea device

Before, tapping home search didn't bring up IME because of no focus.
Now, it will focus home if it is on a different TDA.

Fix: 155000370
Test: manual: verify on a dual TDA device
Test: atest WmTests:WindowContainerTests
Test: atest WmTests:WindowManagerServiceTests
Change-Id: I9c6e815e62ad6f82d6d6b5fbbd361437b40d5e89