mod_http_oauth2: Support granting zero role-scopes It seems Very Bad that if you uncheck all roles on the consent page, you get the default scopes, which seems the opposite of what you probably intended. Currently, mod_tokenauth will do the same thing, so work is needed there too to allow issuing tokens without roles. A token without a role could be used for OIDC login, and not much else. This seems like a valuable thing to support.

Generate a DNS UPDATE order in format suitable for `nsupdate` based on
current port configuration.

Example output:

```
$ prosodyctl mod_dnsupdate -d example.com -t xmpp.example.com example.com
zone example.com
server ns1.example.com
ttl 3600
add _xmpp-client._tcp.example.com IN SRV 1 1 5222
add _xmpp-server._tcp.example.com IN SRV 1 1 5269
```