Refactor logic to reduce the complexity of occluder to a helper function

This CL also moves the logic to determine if quads can occlude other
quads to a helper function as well.

Bug: b:364671921
Change-Id: Id9f3f88127cddfce2008ded6ea9d6ab0d040b8aa
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/6090525
Reviewed-by: Peter McNeeley <petermcneeley@google.com>
Commit-Queue: Zoraiz Naeem <zoraiznaeem@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1396258}