mod_http_oauth2: Reflect ALL attributes of the client registration Per RFC 7591: " Additionally, the authorization server MUST return all registered metadata about this client, including any fields provisioned by the authorization server itself. " The idea is that the server may replace/drop fields in the registration, so what gets reflected back to the client is the source of truth about the registration.

This module writes out a traceback to `traceback.txt` in Prosodys data
directory (see `prosodyctl about`) when the signal `SIGUSR1` is
received. This is useful when debugging seemingly frozen instances in
case it is stuck in Lua code.