[canvaskit] Exposed SkPath::arc. Exposed SkEncodedImageFormat enum. Exposed SkImage::encodeToData overload with arguments

These changes expose the arc function for SkPath. The ApplyAddArc function is a copy from the PathKit bindings.

Also exposed the PNG and JPEG formats from the SkEncodedImageFormat enum and the SkImage::encodeToData overload that accepts format and quality options. The direct binding of encodeToData was replaced with a pre-js wrapper that calls the appropriate private overload

We are working on a PostCSS conic gradient polyfill plugin and want to use the CanvasKit to generate it.
Problem is - it lacks the arc function that technically exists but isn't exposed. And it would be really great to have encodeToData with options since generated PNGs are quite large.
More details on the issue can be found here: https://github.com/jonathantneal/postcss-conic-gradient/issues/10

R=kjlubick@google.com

Bug: skia:
Change-Id: I3f1dc88ad308369fe62004080bcc196c4fbbf742
Reviewed-on: https://skia-review.googlesource.com/c/171046
Reviewed-by: Kevin Lubick <kjlubick@google.com>
Commit-Queue: Kevin Lubick <kjlubick@google.com>
diff --git a/AUTHORS b/AUTHORS
index 016e05a..aa6a5e6 100644
--- a/AUTHORS
+++ b/AUTHORS
@@ -51,3 +51,4 @@
 Yandex LLC <*@yandex-team.ru>
 Kaloyan Donev <kdonev@gmail.com>
 Yong-Hwan Baek <meisterdevhwan@gmail.com>
+Alexander Khovansky <alx.khovansky@gmail.com>