All `.gitignore` files should be ignored by lamdera live file watcher too

[supermario]

Would help improve situations like #105.

That said perhaps we should always include /public statically given it's likely to be gitignored but arguably you would want a refresh for changes in there locally?

[pithub]

Or we introduce .lamdera-ignore - maybe with our own syntax and semantics (simpler than .gitignore)? Otherwise there are a few Haskell packages...

[miniBill]

generated is likely to be .gitignored but you'd still want to watch it.

What if we go at it the opposite way? We watch elm.json and all source-directories and nothing else?