Add login button to header

frontend/src/app/services/auth.service.ts

@@ -112,4 +112,8 @@ export class AuthService {
     const claims = this.userClaimsSubject.getValue();
     return claims?.authorizations || [];
   }
+
+  public hasAccess(authorization: string[]): boolean {
+    return this.getUserAuthorizations().filter(entry => authorization.includes(entry)).length > 0;
+  }
 }