feat(webgl): Enforce WebGPU style topology

[ibgreen]

For #

Background

• Continuous cleanup: Mixed usage of WebGL numeric constants and WebGPU string constants is getting messy.

Change List

• Replace al GL constant based drawMode parameters with topology strings
• Instead of preventing use, now provides named webgl-only constants for draw modes (topologies) and vertex formats, such as triangle-fan-webgl and unorm8x3-webgl
• Calls out lack of portability while allowing apps to adopt new API.

Notes

• will require a quick pass in the deck.gl integration branch as well.