Reland "Split building encoding from decoding"

This reverts commit 9d4b788807fcca010399c0987aed41b3af5d938f.
Copyright issue has been fixed in
https://skia-review.googlesource.com/c/skia/+/275998.

Original description:
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.

TBR=djsollen@google.com

Change-Id: Ic847bae0154e0a2922100b3f2ee14a077ee5635a
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/276007
Reviewed-by: Derek Sollenberger <djsollen@google.com>
Commit-Queue: Leon Scroggins <scroggo@google.com>
diff --git a/RELEASE_NOTES.txt b/RELEASE_NOTES.txt
index 271e2fc..9b7dddc 100644
--- a/RELEASE_NOTES.txt
+++ b/RELEASE_NOTES.txt
@@ -7,6 +7,9 @@
 Milestone 82
 
 <Insert new notes here- top is most recent.>
+  * Make it possible to selectively turn on/off individual encoders/decoders,
+    using skia_use_(libpng/libjpeg_turbo/libwebp)(decode/encode).
+
   * Removed GrGpuResource, GrSurface, and GrTexture from public api. These were not
     meant to be public, and we now can move them into src. Also removed getTexture
     function from SkImage.h