Automatically lint project package and dependencies

[pi0]

Upstream (nypm): unjs/nypm#98

There are frequent issues with multiple versions of hoisted dependencies.

Shared by @QuiiBz, just saw https://github.com/QuiiBz/sherif. I think a package like this could be nice to at least show soft warnings after nuxi upgrade about possible similar issues.

[danielroe]

linking ~> #330

[pi0]

Thanks for the ref. I think it mainly matters for CLI because sometimes we want postupgrade/install checks outside of lifecycle and i imagined it could be part of nypm integration.

Otherwise if nuxt-doctor is going to have a standalone CLI, we can certainly exec it's commands by nuxi 👍🏼

[danielroe]

I think including in CLI is a great idea 👍