Move SkColorTable to src/codec

It is no longer needed anywhere else, and simply happens to be an
implementation detail of SkCodec (at least for now).

Remove references to SkColorTable in other classes, and clean up some
includes of SkConvertPixels I found along the way.

Remove unused includes/methods on SkColorTable

Change-Id: I46c8e46f5b77c37710b6cf595d48107d55871d52
Reviewed-on: https://skia-review.googlesource.com/130845
Commit-Queue: Leon Scroggins <scroggo@google.com>
Reviewed-by: Mike Klein <mtklein@google.com>
13 files changed