Split building encoding from decoding

Bug: skia:9756

In CanvasKit, a large part of the binary is for encoding. Clients
would be happier with a smaller binary and no webp/jpeg encoding. Make
this an option by splitting up the GN arguments.

Split SK_HAS_WEBP_LIBRARY into SK_CODEC_DECODES_WEBP (to match the
existing SK_CODEC_DECODES_RAW) and SK_ENCODE_WEBP. Same for JPEG and
PNG.

Update CanvasKit compile script to disable webp and jpeg encoding.
Update debugger compile script to disable all encoding.

Change IsPng signature to match other SkCodecs.

Change-Id: Iec8466ee1b76bc3d1e377c24201068b776cd7718
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/273768
Commit-Queue: Leon Scroggins <scroggo@google.com>
Reviewed-by: Derek Sollenberger <djsollen@google.com>
Reviewed-by: Kevin Lubick <kjlubick@google.com>
Reviewed-by: Nathaniel Nifong <nifong@google.com>
21 files changed