Allow non-resizable apps in split-screen (6/n)

Trigger TaskInfoChanged when the direct top Activity of the organized
Task enters or exits size compat mode.

This is the prerequisite to move SizeCompatModeActivityController from
system ui to shell. After that, we can render the size compat restart
button on Task Surface similar to split screen divider.

Bug: 176061101
Bug: 178327644
Test: atest WmTests:SizeCompatTests
Test: atest WmTests:WindowOrganizerTests
Change-Id: I0e328796095bc17d40a5ef2f354f291c12ffa04a