Add internal DiscordRole constructor

Created by: armaa

As said in the title, having a public (or rather default..) DiscordRole constructor is obsolete because theres no way to make a new role out of it, as in add/remove permissions to the object itself, and every other entity has this sort of thing to prevent the user to create a new object which isnt possible to edit then in any way, since most of them (if not all) just have getters and no methods to edit/add/remove stuff.