Rework folder structure in frontend

Pages are now grouped per group they appear in on in the header (where possible)
Utilities used by multiple pages in the project are grouped in folders such as services/pipes/etc

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

@@ -1,5 +1,5 @@
 import {Injectable} from '@angular/core';
-import {LoginService} from '../../api';
+import {LoginService} from '@api';
 import {CookieService} from 'ngx-cookie-service';
 import {BehaviorSubject, Observable, throwError} from 'rxjs';
 import {catchError, tap} from 'rxjs/operators';

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

@@ -0,0 +1,14 @@
+import {Injectable} from '@angular/core';
+
+@Injectable({
+  providedIn: 'root'
+})
+export class ScrollService {
+  scrollToTop(): void {
+    window.scrollTo({
+      top: 0,
+      behavior: 'smooth'
+    });
+  }
+}
+