New helpers for SkYUVAInfo when used with pixmaps.

SkYUVAPixmapInfo is a SkYUVAInfo with per-plane color types and row
bytes. It describes a set of pixmaps that make up a planar image.
Consolidates validity checks of the SkYUVAInfo with the color types
and row bytes. It can provide SkImageInfos for each plane and also
assist with configuring planes to share a common allocation.

SkYUVAPixmaps is a collection of SkPixmaps that are valid for a
SkYUVAInfo. It can either wrap existing SkPixmaps or allocate and
own the memory. It consolidates validity checking of SkPixmaps with
the SkYUVAInfo. Replaces sk_gpu_test::YUVAPixmaps.

Minor tweaks to SkYUVAInfo naming, parameter order consistency, adds a
hasAlpha() method.

Bug: skia:10632
Change-Id: Ib0f48b8448fff22805fd0c04e07887d0b7338b76
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/312886
Commit-Queue: Brian Salomon <bsalomon@google.com>
Reviewed-by: Robert Phillips <robertphillips@google.com>
Reviewed-by: Leon Scroggins <scroggo@google.com>
diff --git a/RELEASE_NOTES.txt b/RELEASE_NOTES.txt
index d8ccce5..b98ac93 100644
--- a/RELEASE_NOTES.txt
+++ b/RELEASE_NOTES.txt
@@ -20,6 +20,7 @@
   * New YUVA planar interface in SkCodec. Chroma subsampling is specified in more structured way.
     Doesn't assume 8bit planar values.
     https://review.skia.org/309658
+    https://review.skia.org/312886
 
   * Added VkImageUsageFlags to GrVkImageInfo struct.