Revert "Move ume and mess to homebrew-games"

The `mess` formula was deleted in 3aeecefcaa5a64589c37fdb177a5fb2b2e64d0c1 and moved to homebrew-games.  There was a brief mention of this in #34751 and then it disappeared without much discussion.

MESS is similar to VICE (another Homebrew formula) insofar as it offers full emulators for different computer systems and it does not include any games at all.  These emulators can be used to play game software only if the user obtains games elsewhere and loads them in.  The emulators have many more applications beyond games.

I am using MESS emulators for software development that has nothing to do with games.  The deleted `mess` formula, along with other Homebrew formula such as `acme` and `opencbm`, are my toolchain.  While I could tap `homebrew-games` to get `mess` again, I think it's a misclassification of what this software offers.

@jacknagel @adamv

This PR was made with `git revert`.  The unrelated change to `salt` was made in 3aeecefcaa5a64589c37fdb177a5fb2b2e64d0c1.