story #7299: Return cross references as a field in tracker artifact list for REST

Change-Id: Ia90a3a438075bc645318689953cc11aeb5be6013
Merge commit 'refs/changes/28/2828/5' of ssh://gerrit.tuleap.net:29418/tuleap into stable

* ssh://gerrit.tuleap.net:29418/tuleap:
  story #7299: Return cross references as a field in tracker artifact list for REST
This is Tuleap 7.3.99.29

Change-Id: If3b0468bd688252caef823f91b7a1825402b04f4