Espruino plugin for Rollup module bundler

I think I'd try to create some rollup POC PR for the IDE just to see how that would fare. What do you think?

Yes, that'd be great! If we can fit it in in such a way that the IDE is still responsive I'm definitely up for including it - I just don't want to be in the position where the IDE is 5x the size, slower, and doesn't do all the stuff it did before :)