Support for OAuth Client Login (XEP-0493)

[nioc]

Is your feature request related to a problem? Please describe.
I run a xmpp webapp behind a SSO, I would like to use OAuth for login but I do not think XEO-0493 is supported in xmpp.js?

Describe the solution you'd like
Allow to instanciate client with a token provided by my IdP and then XMPP server attempts to validate it using the configured validation endpoint.

Additional context
See XEP and Prosody modules:

• https://modules.prosody.im/mod_auth_oauth_external.html
• https://modules.prosody.im/mod_auth_oauthbearer.html