Allow non-resizable apps in split-screen (10/n)

Render size compat restart button on Task surface with
WindowlessWindowManager.

Bug: 176061101
Bug: 178327644
Test: atest WMShellUnitTests:SizeCompatRestartButtonTest
Test: atest WMShellUnitTests:SizeCompatUIControllerTest
Test: atest WMShellUnitTests:SizeCompatUILayoutTest
Change-Id: I86912adca18a6a62265cd31585f2c7d612c90fd1