SERAC: filter by contributor

We got a request per email: a Mountaineering club wanted to use SERAC for their RETEX. For their own purpose, they want to be able to extract the reports that are related to their club only.

Request: filter Xreport by user.

Implementation: few possibilities (they can be combined)
- add a filter by user on [the Xreport page](https://www.camptocamp.org/xreports), like the multicriteria filter for the [outings](https://www.camptocamp.org/outings).
- add a link on the [user profil page](https://www.camptocamp.org/profiles/384121/), between "outings" and "contributions" on the left. Possibility to show it only for profils of the type club/association.
- add a private link "my Xreports" in the upper right menu, between "my contributions" and "my friends".

The choice should take care of privacy of users.