Add idea of DataType to SkYUVAPixmapInfo.

DataType describes the data type of YUVA channels
independent of how they are grouped into planes.

Adds mapping functions between SkColorType/channel count
and DataType.

SkYUVAPixmapInfo can be constructed from DataType and will
choose appropriate SkColorTypes for each plane.

Valid SkYUVAPixmapInfos now have the same DataType for each
plane (could relax this in the future, esp for alpha plane).

SkYUVAPixmapInfo::SupportedDataTypes specifies the supported
combinations of SkYUVAInfo::PlanarConfig and
kYUVAPixmapInfo::DataType supported by a GrContext (based on
supported texture formats).

SkImageGenerator/SkCodec YUVA query API now takes a
SupportedDataTypes.

Change-Id: I8791234638e6ba3396d1e7960b7bc210edc6dd57
Bug: skia:10632
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/314276
Reviewed-by: Leon Scroggins <scroggo@google.com>
Reviewed-by: Robert Phillips <robertphillips@google.com>
Commit-Queue: Brian Salomon <bsalomon@google.com>
19 files changed