DisplayCutout: Support more than one cutout

Also makes API more restrictive. Also moves window manager specific
logic out of the framework. Also fixes SystemUI such that it can properly
deal with more than one cutout.

Bug: 74195186
Test: atest DisplayCutoutTest WmDisplayCutoutTest DisplayContentTests WindowFrameTests
Change-Id: Ib7b89e119ce2d3961687579bb81eadce1159a600