Separate and add more SizeCompat tests; add Display Builder

The number of SizeCompat tests is growing so this
separates them out into their own class. Additionally,
it streamlines display and activity creation for the
variety of scenarios that need testing and facilitates
consistent display creation for tests (previous code
would create displays based on the device display which
meant the tests would potentially test different things
on different devices).

Also added a Builder to TestActivityDisplay. This
makes it possible to create displays with/without notch
and custom windowingmode/rotatibility/density/etc.

Also fixed a small bug where aspect-ratio was calculated
incorrectly.

Some SizeCompat tests were added too:
 testFixedAspOrientChangeOrient to verify that a sizecompat
   app can still change fixed orientation properly
 testMoveToDifferentOrientDisplay to verify that a sizecompat
   app properly moves between different non-rotateble displays
 testLetterboxFullscreenBounds to sanity check that sizecompat
   apps start properly when letterboxed by policy
 testFixedOrientRotateCutoutDisplay to verify that a sizecompat
   app stays fixed when on a rotating display with cutout.

Bug: 138594779
Test: this
Change-Id: Ic78374ae9e58297c609349c382efc6738521872c