ScarpetEdit should take user's native language on startup

[Ghoulboy78]

Before February, I had planned on doing this, even going so far as to implement gnembon/fabric-carpet#824, but kinda left it off thereafter.
After coming back to it, I realise that this is simple. First, we need to check that the player's given language is actually an available option, and next we need to change. Im not quite sure exactly how hard each of those two would be, so I'm leaving it open for anyone to do (cos Im kinda lazy and rly busy).