Rework maxRenderTargetSampleCount and isFormatRenderable in GrCaps.

With this maxRenderTargetSampleCount only takes a GrBackendFormat and
returns a sample count based on that only. If a caller wants to know if
a given Format and GrColorType pair is renderable they should use
isFormatRenderable which now also takes a desired sample count.

This change also allows the removal of GrPixelConfig version of
maxRenderTargetSampleCount and internalMultisampleCount.

Bug: skia:6718
Change-Id: I563c61f8349e56f6681378170a45f33ac5cddfa9
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/231558
Commit-Queue: Greg Daniel <egdaniel@google.com>
Reviewed-by: Robert Phillips <robertphillips@google.com>
18 files changed