Cabal should warn more strongly about outdated hackage indexes

[noughtmare]

Inspired by this stack overflow issue.

Cabal does warn about the package index being out of date, but that is all the way at the top and not very prominent.

I see a few avenues for improvement:

• use colors
• add empty lines before and after the warning
• add an extra warning if the latest version of a required package is lower than a version mentioned in the bounds

Especially the last point could make a huge difference in my opinion. Specifically, in the stack overflow question linked above the problem is that cardano-wallet requires blockfrost-client-core>=0.4 && <0.5, but the latest version in the index is blockfrost-client-core-0.2.0.0. In this case cabal could again strongly recommend that the user run cabal update at the end of the resolution phase.

Furthermore, I think the whole output is quite cluttered, but I will leave that for another issue in the future.