VTVideoDecodeAccelerator: Represent P010 frames as multi-planar

Also ensure that the planes of these frames are represented by
GL_RED and GL_RG, and kA16_unorm_SkColorType and
kR16G16_unorm_SkColorType.

Bug: 1233228
Change-Id: I077d35ff250153fdfde933e4249d9a3a38947ada
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/3925700


Reviewed-by: Dan Sanders <sandersd@chromium.org>
Commit-Queue: ccameron chromium <ccameron@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1054199}