Check for scopes

[bunysae]

Description

Check for scoped packages when publish to a
private registry as mention in https://github.blog/2021-02-12-avoiding-npm-substitution-attacks.
When a non-scoped package is published to a private registry, np could throw a warning.
I think we can win security and can avoid malicious failures as mention in the blog-post.

[sindresorhus]

Check what exactly? The issue description should be self-explanatory without needing to read the whole blog post.