story #7174: Update BacklogItemRepresentation with cards semantic

Change-Id: Ib80fd3bfa98458b88c61a3490d6c29214d9f6649
Merge commit 'refs/changes/60/3360/10' of ssh://gerrit.tuleap.net:29418/tuleap into stable

* ssh://gerrit.tuleap.net:29418/tuleap:
  story #7174: Update BacklogItemRepresentation with cards semantic
This is Tuleap 7.8.99.15

Change-Id: Ib0d5dc9b59873fbb2d2284926f063f97aaf69cef