mod_rest/rest.sh: Update to use httpie-oauth2 plugin This bash implementation of OAuth2/OIDC was growing to the point where it needed a massive refactor, which made me look into alternatives where I finally settled on implementing oauth2 in a plugin for HTTPie.

This module discards typing notifications sent to a bare host JID,
preventing error replies to be sent. These errors are harmless but can
be annoying sometimes if your client shows them prominently.