chore: Add nebula.gl modules

[ibgreen]

This PR forks nebula.gl into this repo withe the following module mapping:

nebula module (path)	Description	Forked module
nebula.gl (modules/main)	The core module	=> deck.gl-editable-layers
@nebula.gl/edit-modes (modules/edit-modes)	Optional edit modes	=> deck.gl-editable-layers
@nebula.gl/layers (modules/layers)	The actual layers	=> deck.gl-editable-layers
@nebula.gl/editor (modules/editor)	React wrapper	=> react-deck.gl-editable-layers
@nebula.gl/overlays (modules/overlays)	React General overlays	=> react-deck.gl-editable-layers
react-map-gl-draw (modules/react-map-gl-draw)	Non-deck-wrapper	=> NOT FORKED

[chrisgervang]

This module grouping makes sense to me. I can imagine most of the features in react-deck.gl-editable-layers being implemented as a deck.gl widget, which would work for both react and pure-js applications.

[ibgreen]

Yes I think the goal should be to sunset / remove the react module if at all possible. Whatever it offers should be available to all bindings.

• We should create a list of reasons why it is needed and brainstorm about ways we can solve those needs in react-independent ways.