Add McAdmin Copy command

Added: /mcadmin copy from-uuid to-uuid. This command allows you to copy player data from one UUID to another, as players may need to copy data over from an old account due to the enforced MS migration. At the moment, both players must be offline for this command to work. You can run the command either through console or in game with the permission mcadmin.copy. This adds new strings to the en.yml as well automatically to support this new command.