(Draft) Initial game mode POC

[MattEqualsCoder]

This is a very, very early POC to get a rough idea of what I had in mind for how different game modes could work. This uses the game mode system for keysanity. Perhaps not the best example because the dealings of keysanity are rather broad with so many things that utilize the configs, but still.

Still, with the keysanity game mode, it actually customizes the item pools to remove the compasses and maps that are unnecessary, adds the patches, and even automatically tracks the dungeon rewards once the maps are collected. I'm also contemplating adding in a mechanism for modifying tracker lines and whatnot as well.

Note that this doesn't actually implement any UI for changing these settings. Again, this is a POC for you all to see the code to offer thoughts on the overarching approach before I go too deep into this.