[feature] separate Freedoom autoload directories from doom*-all/

[elf-alchemist]

When running Freedoom as an IWAD, the contents of doom*-all/ are read as well, I happen to keep at least my M_* text graphics in doom-all/ so no matter what they show up ingame. And previously I had other graphics in doom1-all/ and doom2-all/ which also conflicts with freedoom1.wad, freedoom2.wad and freedm.wad

With just doom-all/:

Also including doom2-all/:

Similarly to doom*-all/ I personally believe it should have it's own set of three (or at least just freedoom-all/) and also remove it from triggering the doom*-all/ trio