*: use npm workspaces

[tharvik]

• no need for npm link anymore
• allow to build all projects via npm -ws run build (or test, or any script really)
• allow to easily import packages (simply import @epfml/disco-core) by using a common node_modules for shared deps
• watch files changes and run npm script in most packages, for eg npm -w ./discojs/discojs-core run watch build
• change much of the github action to better reflect the stages dependencies (we can't lint discojs-core without build discojs-node for example)

[JulienVig]

Amazing! Can you update DEV.md with an updated install.sh description?
Edit: never mind, I need to merge the documentation branch beforehand

[tharvik]

Amazing! Can you update DEV.md with an updated install.sh description?

Thanks, yep, will do!

I will also first discuss it with @peacefulotter as it probably conflicts with the bun integration PR.

[tharvik]

I've also added a way to watch for changes and build/lint/test accordingly. One can use it via npm run watch build in every pkg.

[JulienVig]

Very nice! This is going to make things so much smoother, thanks! I left a few non-blocking questions and suggestions.