feat: add functionality for codes component (#309)

src/app/system/system.service.ts

@@ -0,0 +1,28 @@
+/** Angular Imports */
+import { Injectable } from '@angular/core';
+import { HttpClient, HttpParams } from '@angular/common/http';
+
+/** rxjs Imports */
+import { Observable } from 'rxjs';
+
+/**
+ * System service.
+ */
+@Injectable({
+  providedIn: 'root'
+})
+export class SystemService {
+
+  /**
+   * @param {HttpClient} http Http Client to send requests.
+   */
+  constructor(private http: HttpClient) { }
+
+  /**
+   * @returns {Observable<any>} Fetches Codes.
+   */
+  getCodes(): Observable<any> {
+    return this.http.get('/codes');
+  }
+
+}