[New Check]: Report packages without a maintainer in `pkgcheck scan --commits`

[mgorny]

Is there an existing such new check request for this?

• [X] I have searched the existing issues

Explain

I think a (informational) result about packages without a maintainer would be useful. Especially for pkgcheck scan --commits, when I bump some packages in dev-python/ and fail to notice they have no maintainer (but they're fit for python@).

Examples

No response

Output message

Package has no maintainer

Documentation

No response

Result level

info