mod_http_oauth2: Allow only l10n variants of name in client metadata Since "client_name" seems to be the only human readable non-URI property that makes sense to have localized version of. Therefore it seems excessive to allow arbitrary additionalProperties. We don't make use of localized versions of client_name and URIs yet, but it would be nice to do so.

Removes invalid characters from roster entries.

```bash
sudo prosodyctl mod_clean_roster
```