Refactor gitolite permissions serialization

Needed to introduce permissions for mirrors

Part of story #7514 - have grokmirror hook activated

Change-Id: I18fcabb9911e4e077b8f59e532d67f4165fef75d
On mirroring, grant mirror user read permission on repository

Part of story #7516 have my repositories replicated on selected mirror

Change-Id: Ib1bfa8226b0521e3f9ca71ef0b327c01165b48c1
Merge commit 'refs/changes/06/3106/6' of ssh://gerrit.tuleap.net:29418/tuleap into HEAD

* ssh://gerrit.tuleap.net:29418/tuleap:
  Refactor gitolite permissions serialization

Change-Id: I9326d0d86b6596aab6595b066f9dba50744ee871
This is Tuleap 7.5.99.59

Change-Id: Ie2c375c41329584f8a52724b368d1f9b095866d9
Merge commit 'refs/changes/07/3107/6' of ssh://gerrit.tuleap.net:29418/tuleap into HEAD

* ssh://gerrit.tuleap.net:29418/tuleap:
  On mirroring, grant mirror user read permission on repository

Change-Id: I8f63cee13a3ea009f8efe75e08ef9aad4f3c4dd6
This is Tuleap 7.5.99.60

Change-Id: I75bd7595e87272de3726226f63ce8fac5d5e3408