story #7325: see the correct mirror information for a git repository

- user can switch between mirrors and have the repository url changed accordingly
- new "identity" property for each mirror
.
Change-Id: I732bac539079cf66650d4353ae044ec5903d223e
Merge commit 'refs/changes/06/3206/27' of ssh://gerrit.tuleap.net:29418/tuleap into tuleap-stable-master

* ssh://gerrit.tuleap.net:29418/tuleap:
  story #7325: see the correct mirror information for a git repository

Change-Id: I417364a47260f6ab6fd4800ecdecffb73a16d744
This is Tuleap 7.7.99.9

Change-Id: I45b4ba6ef7c65bcf24a25586a945e14f65f72691