feat: add manage surveys component (#343)

Fixes #186

src/app/system/system.service.ts

@@ -46,6 +46,13 @@ export class SystemService {
     return this.http.get('/codes');
   }
 
+  /**
+   * @returns {Observable<any>} Fetches Surveys.
+   */
+  getSurveys(): Observable<any> {
+    return this.http.get('/surveys');
+  }
+
   /**
    * @param {any} code Code to be created.
    * @returns {Observable<any>}