[AAE-4966] Extensible app config (#6914)

* merge app config from the extensions

* improved service injection in unit tests

* extra unit test

* fix content tests

* update code as per review

* fix lint

* fix lint

* update code and tests

* update schema

lib/core/services/nodes-api.service.spec.ts

@@ -45,6 +45,9 @@ describe('NodesApiService', () => {
                 getNodeChildren: jasmine.createSpy('getNodeChildren'),
                 addNode: jasmine.createSpy('addNode')
             }
+        },
+        isEcmLoggedIn() {
+            return false;
         }
     };