Add dockerimage to ease local development

[avivace]

trafficstars

I would like to provide a basic dockerimage able to build the deps to wasm so local development gets a bit easier.

I'm working (https://github.com/gbdev/rgbds/pull/1167) on one for RGBDS which could constitute the base image for this.

[avivace]

https://github.com/gbdev/rgbds/pull/1167 is done so here we could just base the image on that, add Node and we've a development environment building/serving rgbds-live