Support Skia shaders (SkSL)

[igordmn]

https://github.com/google/skia/blob/master/src/sksl/README

Open questions:

• Does SkSL work only with OpenGL, or also with different backends (DirectX, Metal, software)?
• We currently draw into temporally SkPicture to avoid concurrency issues on macOs (on macOs we can render only in AppKit thread, but our UI should work in AWT Thread). If SkPicture isn't supported with SkSL, how can we provide render API for Compose?
• How can we pass bitmaps (textures) into shader?

[rock3r]

Looks like you can already use SlSL shaders in CfD (see this example from kirill-grouchnikov/artemis). Would be nice to get IDE support for the SkSL language.

[okushnikov]

Please check the following ticket on YouTrack for follow-ups to this issue. GitHub issues will be closed in the coming weeks.