Rewrite the config screen (again)

[EnnuiL]

After a slow process of aging alongside a positive historic of improvements to Minecraft's GUI system, as well as concerns about its maintainance, SpruceUI is unfortunately not suitable for us anymore;

Solution? Throw it away and make our own config screen! Unfortunately it is quite the undertaking considering that vanilla screens aren't really the simplest thing ever, and if you want to do a well-built one? You must also implement the accessibility tree

Progress has been made on one, but yeah, I doubt I'll ever manage to finish this myself