Validate community adder's version of `@sveltejs/cli-core`

[AdrianGonz97]

We'll need to validate that the downloaded community adder is running a similar version of @svelte-cli/core as the executing instance of sv. If it fails, we'll prompt the user to update their version of sv.

For version comparisons, we can probably use https://github.com/lukeed/semiver or https://github.com/npm/node-semver

[manuel3108]

Is this the same as #35 or are the titles only closely related?

[AdrianGonz97]

no, #35 is only about adding a warning if there's a newer version of sv available (similar to what pnpm does every time you run it)

[benmccann]

I think it would be nicer if we could avoid breaking them. If we do something like #77 we probably would not need to check the version