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.

Over the years, some servers stop working for various reasons, and leave
behind broken roster subscriptions that trigger failing s2s connections.
This module allows cleaning up such cases by unsubscribing local users
from their contacts on those servers. Also works for typos and the like.
Use with care.

```lua
Component "gmail.com" "unsubscriber"
```