Fix openproject.api module dependencies

So that the wpCacheModule is found in the tests.

frontend/app/angular-modules.ts

@@ -136,6 +136,7 @@ angular.module('openproject.layout.controllers', []);
 
 export const opApiModule = angular.module('openproject.api', [
   'restangular',
+  'openproject.workPackages',
   'openproject.services'
 ]);
 

frontend/app/components/work-packages/work-package-cache.service.ts

@@ -27,7 +27,7 @@
 // ++
 
 
-import {openprojectModule} from "../../angular-modules";
+import {opWorkPackagesModule} from "../../angular-modules";
 import {WorkPackageResource} from "../api/api-v3/hal-resources/work-package-resource.service";
 import {ApiWorkPackagesService} from "../api/api-work-packages/api-work-packages.service";
 import IScope = angular.IScope;
@@ -71,4 +71,4 @@ export class WorkPackageCacheService {
 
 }
 
-openprojectModule.service('wpCacheService', WorkPackageCacheService);
+opWorkPackagesModule.service('wpCacheService', WorkPackageCacheService);