[FEATURE] Show warning when publishing package larger than 10MB

[ondrejsevcik]

There is a lot of packages published in npm registry with build stuff and some other dev dependencies that are not required and just add on size. That's why .npmignore was introduced.

It is surely great feature, but the problem is that many devs don't even know that they are publishing a large package. It would be great to show a warning when someone publishes a package that is larger than 10MB.