Title ^.
Per request of Dunedan: https://wildfiregames.com/forum/topic/88125-call-for-participation-lobby-account-password-change-functionality/
This is relatively bare-bones, but I've tested it to work. Ideally we'd have slightly better UX but I've had limited time today.
Compare to P288, this doesn't check for password in C++ - the XMPP standard mandates that password must be present and non-empty.
I also remove the 'disconnect', as per the standard https://xmpp.org/extensions/xep-0077.html#usecases-changepw this re-uses the registration path, and it seemed awkward. Furthermore, the JS disconnects anyways on registration.
As for UI, I re-use the 'mark buddy' button when clicking on your own profile. See screenshot below.