Refine isLightBarAllowed

The light bar is only allowed if the color-controlling window has
intersection with the system bar.

The app window frame doesn't need to 'contains' the frame of the bar,
because:
1. In split-screen mode, the app window only intersects a part of status
   bar.
2. When navigation bar is at the same side of a display cutout,
   navigation bar would be thicker than the cutout. The app window which
   fits the cutout can only intersect with a part of navigation bar.

Fix: 183696228
Test: atest LetterboxTest LightBarTests DisplayPolicyTests
Change-Id: If17a2050b22e674bb760d6c98305ee69067b11fe