mod_http_oauth2: Reject non-local hosts in more code paths We're not issuing tokens for users on remote hosts, we can't even authenticate them since they're remote. Thus the host is always the local module.host so no need to pass around the host in most cases or use it for anything but enforcing the same host.

This module helps make BOSH and WebSocket connection endpoints
discoverable via the HTTP method described in
[XEP-0156](https://xmpp.org/extensions/xep-0156.html#http).