Reimplement GitLab trigger handler using the V4 API library

GitLab has deprecated and removed the V3 API entirely

Fixes https://jira.coreos.com/browse/QUAY-966

static/js/directives/ui/manage-trigger/manage-trigger.component.html

@@ -35,7 +35,7 @@
               <img class="namespace-avatar" ng-src="{{ ::item.avatar_url }}" ng-if="::item.avatar_url">
               <span class="anchor"
                     href="{{ ::item.url }}"
-                    is-text-only="::!item.url">{{ ::item.id }}</span>
+                    is-text-only="::!item.url">{{ ::item.title }}</span>
             </script>
           </cor-table-col>
           <cor-table-col title="Importance"