Small cleanup of lit-plugin errors

[Misiu]

I've added recommended extensions (same as in HA Frontend). I've also removed some (not all) lit-plugin errors. I'll try to clean the rest in the next PR (plus replace confirm update all with a proper dialog)

[Misiu]

any ideas why npm exec -- prettier --check src in github actions only shows 3 files, but locally (windows 10) I get 81 files? I'm also formatting files via Prettier locally before every commit, but I get errors every time CI runs on github. Probably because of different settings.