Detect competing sdd directories and warn about them

[NortySpock]

just doctor now warns if it finds more than one .ssd folder with a modinfo that overlaps.

Game directory (.sdd conflicts)
[warn]  Multiple .sdd folders share the game name "Beyond All Reason":
[warn]      /home/user/.var/app/info.beyondallreason.bar/data/games/tmp_archive/BAR.sdd
[warn]      /home/user/.var/app/info.beyondallreason.bar/data/games/Beyond-All-Reason.sdd
[info]    Recoil loads only ONE of these (by scan order); the rest are ignored.
[warn]  Your devtools symlink (/home/user/.var/app/info.beyondallreason.bar/data/games/Beyond-All-Reason.sdd) is competing with another copy.
[warn]  The engine may load the OTHER copy, so branch/feature changes in your
[warn]  linked repo may appear ignored.
[warn]  Delete or move the competing .sdd folder and re-run the game.