notice and friends generate interleaved output when used concurrently

[`notice`](https://www.haskell.org/cabal/release/latest/doc/API/Cabal/Distribution-Simple-Utils.html#v:notice) and similar functions generate interleaved output when used concurrently.

This is due to the use of `hPutStrLn`.

It makes writing Cabal hooks that do things in parallel a pain.

It also makes `strace`ing cabal very annoying because it pollutes the outuput.

As a solution, we should use something like `say`, that prints the entire contents in one go and ensures no interleaved output.

Start by locating the Cabal implementation of notice and the similar output functions, then inspect where they use hPutStrLn. Compare that behavior with the mentioned say approach and verify concurrent output, including the strace-related output concern, is no longer interleaved.

Written by the indexing model from the issue text.