Allow loading a local folder when working on the repl

[unlocomqx]

Describe the problem

Editing in the repl can never match editing on your favorite editor/IDE

Describe the proposed solution

Use the "File System Access API" to allow the user to load a local folder (I can provide a PR for this if you think it's a good idea)
This would allow the user to edit files locally and the changes will be synced to the repl and vice-versa

Alternatives considered

I didn't find a workaround

Importance

would make my life easier