New admin endpoint GET /users/v1/reported-users

[j3k0]

The goal is to retrieve the list of highly reported users.

For this task, we first will need the Events /latest feature implemented: https://github.com/j3k0/ganomede-events/issues/31

The idea will be this:

1. retrieve a large number of the last events in the "Events" database, channel users/v1/blocked-users. Maybe the last 10,000.
2. Process this list to count the number of reports per user.
3. For each reported user, check if he is banned (logic for this already part of ganomede-users).
4. Sort descending, only returning users that are not banned.

[j3k0]

Add a config for the number of events to process.