Refactors helper methods related to rounded-display mask textures

This CL does following changes:
1. Make GetRoundedDisplayMasksBounds static method of TextureDrawQuad
instead of OverlayProposedCandidate.
2. Make GetRoundedDisplayMasksBounds take pointer to a DrawQuad
as argument instead of taking OverlayProposedCandidate.
3. Move tests that are related to GetRoundedDisplayMasksBounds().
4. Introduce a new static method QuadHasRoundedDisplayMasks() for
OverlayCandidate.

Bug: b/341369047
Change-Id: I8a4e916b4433e010a3939cae471c4feaf66fd4ea
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5548658
Reviewed-by: Peter McNeeley <petermcneeley@chromium.org>
Commit-Queue: Zoraiz Naeem <zoraiznaeem@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1305519}