UI ember engines (#6718)

Adds replication engine and core in-repo addon

ui/lib/replication/addon/routes/mode/secondaries/add.js

@@ -0,0 +1,27 @@
+import { hash } from 'rsvp';
+import Base from '../../replication-base';
+
+export default Base.extend({
+  model() {
+    return hash({
+      cluster: this.modelFor('mode.secondaries'),
+      mounts: this.fetchMounts(),
+    });
+  },
+
+  redirect(model) {
+    const replicationMode = this.paramsFor('mode').replication_mode;
+    if (!model.cluster.get(`${replicationMode}.isPrimary`) || !model.cluster.get('canAddSecondary')) {
+      return this.transitionTo('mode', replicationMode);
+    }
+  },
+
+  setupController(controller, model) {
+    controller.set('model', model.cluster);
+    controller.set('mounts', model.mounts);
+  },
+
+  resetController(controller) {
+    controller.reset();
+  },
+});