CLI for validating project

Is your feature request related to a problem? Please describe.

Add a new package to the mono-repo which could be something like svelte-check. Perhaps being extra verbose is good here, because I’m not certain that in the long term this module would be the place where it lives. (e.g. I think if there’s a svelte cli, then this would be a subcommand in there.

Describe the solution you’d like

The package would use the LSP shipped in this repo to ping every Svelte file in the current directory, and to request diagnostics (a.k.a errors) for that file. This is effectively the equivalent of running TypeScript and/or other tools we support in the LSP over each file.

Describe alternatives you’ve considered In theory this could be built without the LSP, but that abstraction is solid and already has proven itself in vetur

Additional context Came out of https://github.com/sveltejs/svelte/issues/4518#issuecomment-625345746

[dummdidumm]

Now live at https://www.npmjs.com/package/svelte-check

[orta]

I don’t know enough about how people use Svelte to talk about that middle step, in my head all of that was happening at IDE level but it seems to make sense

But yeah, that’s basically the entire gist 👍