WebGL support #579

Consider adding WebGL layer (<WebGL> / <Layer type="webgl">) and primitives support, although Svg, Canvas, and Html typically fulfill most needs, and there is more performance opportunity to unlock.

Might be able to leverage an abstraction to simplify implementation

• https://github.com/karellodewijk/canvas-webgl
• https://github.com/jagenjo/Canvas2DtoWebGL
• https://g.antv.antgroup.com/en

Note: WebGL does have a limit on the number of concurrent WebGL contexts (also mentioned by uPlot and Rive).