Make commands public to use them in other mods

[jblemee]

With these changes, we can write this kind of code in custom mods:

 ResourceLocation resourceLocation = ResourceLocation.read("my:world").getOrThrow();
 ResourceKey<Level> resourceKey = ResourceKey.create(Registries.DIMENSION, resourceLocation);
 RTPDCommand.runCommand(player, server.getLevel(resourceKey));

Which allow modders to forbid the use of rtp commands directly by the player but enable it through custom mod conditions