Split SkYUVAInfo::PlanarConfig into PlaneConfig and Subsampling enums

Sometimes it's helpful to think about subsampling separately from
how the channels are spread across planes.

Bug: skia:10632
Change-Id: Ib03f71195f9706ef6def418b1f2125c29e0cf738
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/334102
Commit-Queue: Brian Salomon <bsalomon@google.com>
Reviewed-by: Jim Van Verth <jvanverth@google.com>
Reviewed-by: Robert Phillips <robertphillips@google.com>
15 files changed