[Feature] Add a foreign (`-f`) option to `purge-roms`

[TylerVigario]

Would be nice if we could check (and optionally delete) foreign ROMs within managed folders.

EDIT 1/15/24: If this is the meaning of orphan, then for whatever reason, I found it keeping extra bin files even though I have a CHD for the game. I could imagine normal files (.bin, etc) might not be considered "orphan" if we do not check for the existence of another format (i.e. 7z, zip, CHD, ISO, etc)

[alucryd]

Orphan files are files known to the database, meaning they were at some point associated with a game/rom but no longer are. So foreign files would be files that are present in the rom directory tree, but not in the database.

Sounds like a post-conversion cleanup might have failed if you have BINs still lying around. Nevertheless it's a good idea and shouldn't be hard to implement. Will handle that after I'm done with the post conversion checks. I'm finally learning and using traits in rust, so that one is taking longer than expected while I get a good grasp on the feature and how to make clever use of it in this context.

[alucryd]

Added in https://github.com/alucryd/oxyromon/commit/76ab5c2b8fd635c996384d5da6720efa1a45f485

Unlike the other flags, this one will prompt you for every foreign file found, as you might want to keep some of them, like translation patches.

[TylerVigario]

@alucryd I Just tested it, and it works great! I agree that each deletion should be explicit.