size-limit --check

It's time to think about the next 2000 stars:
- size-limit for `libraries` and `apps` (two different configs)
- `size-limit --check` as an extension of `--why` to check not the size, but size factors

Size factors:
- Library: using __dev dependencies__ as dependencies. They do not affect the bundle size, so invisible for _normal mode_, but greatly affect the _package install size_, which should be proportional to the bundle size, not 1000 times larger (I am guilty).
- Application: [there is a list of easy wins](https://github.com/GoogleChromeLabs/webpack-libs-optimizations) to reduce package size. There are also [other](https://github.com/theKashey/jsx-compress-loader#other-ways) [plugins](https://github.com/theKashey/runtime-compress-loader#other-ways) to make your app smaller depending on its nature. More to come (once someone asks), and it should be easy to keep it up to date, as long as there are the people (@ai, @iamakulov, @jpnelson, 👀) who care much about it.

It would be great to ask `size-limit` to `check` my Library or App, and be given some advice on how to make it smaller or faster. That's worth next 2k⭐️!