mod_http_oauth2: Declare additional client registration fields as strings Previously any property not listed in the schema was allowed in any form, which is probably a bit too liberal. Instead, limit extra fields to simple strings, which should still allow localized versions of the various URIs and descriptive properties per RFC 7591 §2.2

This module produces more detailed HTTP logs for Prosodys built-in HTTP
server. The format is similar to that of Apache and go into Prosodys
normal logs at the `info` level.