1. aggregators.ts: Added in PortalAggregators.disabled object, service entity & route.
2. app.component.ts: Added in menuItems "Serive" and use for menuItems entity names from OpenaireEntities.
3. app-routing.module.ts: Added routes for service landing, search and advanced search pages.
4. environments/: Added values for properties searchLinkToService, searchLinkToServices, searchLinkToAdvancedServices, errorLink
5. [NEW] Files added for services landing, search and advanced search pages: landingPages/service/, advancedSearchServices.component.ts, advancedSearchServices.module.ts, advancedSearchServices-routing.module.ts, searchServices.component.ts, searchServices.module.ts, searchServices-routing.module.ts
