Idea: HTML5 compliant API

[Danielku15]

Having a full HTML5 canvas compatible API could be quite a big benefit for many others and alphaSkia has big potential for that.

• API similar to OffscreenCanvas for image creation and drawing. (only 2D context, maybe some features not supported initially if they bloat the lib or are not built into Skia already)
• FontFace for handling fonts.
• Additional APIs:
  • like image saving (alternative to toDataURL)
  • Accept types like FontFace as setter for fonts (not only CSS string encoded font descriptions)
  • Unloading of fonts.