mod_http_oauth2: Allow 'login_hint' as a substitute for OIDC 'select_account' prompt If the OIDC 'prompt' parameter does not contain the 'select_account' then it wants us to skip account selection, which means we have to figure which account to authenticate somehow. One way could be have this stored in a cookie from a previous successful login. Another way would be to have the account passed as a hint, which is what we add here.

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"
```