Custom raster gpu pass injection

[kylebarron]

The deck.gl SimpleMeshLayer, just like the BitmapLayer, have a DECKGL_FILTER_COLOR injection point: https://github.com/visgl/deck.gl/blob/a15c8cea047993c8a861bf542835c1988f30165c/modules/mesh-layers/src/simple-mesh-layer/simple-mesh-layer-fragment.glsl.ts#L32.

We may be able to leverage that injection point as shown in numeric-data-layer: https://github.com/developmentseed/numeric-data-layer/blob/316fd69725ec27812c36fd3eb6836de3f9bec75c/packages/numeric-data-layer/src/layers/NumericDataPaintLayer/index.tsx#L56-L71

Note how the uniforms are injected in: https://github.com/developmentseed/numeric-data-layer/blob/316fd69725ec27812c36fd3eb6836de3f9bec75c/packages/numeric-data-layer/src/layers/NumericDataPaintLayer/index.tsx#L81-L87

ref: https://deck.gl/docs/developer-guide/custom-layers/writing-shaders#fs