Add ftb tweaks game mode functionality

[xSaucychan]

Your GTNH Discord Username

saucy4869

Feature Request

Add ftb tweaks game mode switch function into server utilities. Modpacks such as FTB infinity which take advantage use an older version of FTB library which is incompatible with the one bundled in server utilities. Mod should be under same license as the rest of the FTB mod suite; but haven't found a way to confirm https://github.com/Jaredlll08/FTBTweaks

Final Checklist

• I have searched the issues and haven't found a similar issue.