Basic Altening support

[ShayBox]

This adds basic TheAltening support, though it works the head preview doesn't and it says Microsoft for some reason, maybe someone can help.

Update: The head preview works after restarting, just not in the current session after adding account

I don't have any mojang accounts anymore to test to see if there's any side-effects, if someone could test and confirm mojang logins still work after adding an altening account.