DisplayCutout: do not animate cutout (and rounded corner) overlay during rotation

Moves the rounded corner overlay to the overlay layer to prevent it
from getting rotated, since physical features of the display cannot
rotate.

Note that they are still below the screenshot, so not visible during
the transition (because the buffers are not synchronized to the rotation
properly yet).

Also makes sure that only priviliged processes can do this, because the
overlay layer can obscure SystemUI.

Bug: 76102595
Test: Enable cutouts, rotate screen, verify cutout overlay does not participate in the animation
Change-Id: I65dd0bc5b038cca2ba4265c7e7dc93f3264c4d89