Add nested groups support to Git ECA validation checks

Currently we only support legacy checks, which will soon no longer be updated. We should switch to use the new system when checking Gitlab requests.

added Enhancement label

assigned to @malowe

added statereview label

mentioned in merge request !84 (merged)

mentioned in commit b97f2815

mentioned in commit 5c317d45

added statedone label and removed statereview label

closed