Let each window has its own requested insets state

Otherwise, all windows would reference to the same InsetsState object
which is referenced by InsetsStateController.mState.

Bug: 111084606
Test: Open any app in the new insets mode, and see if the status bar
      color view is shown as expected.

Change-Id: I04ca3aaa7c40c77c9022f52aee0579593fd4696b