Hidden configuration editing

[EpicKnarvik97]

While being able to edit hidden configurations like any other configuration would be dangerous, it would make sense to have a hidden command to edit those configuration values.
A command such as /sgc hiddenconfig should not be available in tab completion, but should work if typed correctly. It would expose a list of only the hidden configuration values. The existing ConfigCommand class should be modified to be able to modify the hidden configuration values, without duplicating code.