fix: Sidans titel ändras nu korrekt när man går tillbaka till startsidan. (TV-643)

Squashed commit of the following:

commit b70383f449eb2e17e0da2e479316c821cdf4bb85
Author: Daniel Appelgren <daniel.appelgren@arbetsformedlingen.se>
Date:   Wed Sep 22 15:04:38 2021 +0200

    fix: Flyttade titlesättning från layout.component till app.component. Krävde mer logik för att hitta vilken route man är på. (TV-643)

apps/mina-sidor-fa/src/app/app.component.ts

@@ -1,6 +1,9 @@
 import { DOCUMENT } from '@angular/common';
 import { ChangeDetectionStrategy, Component, Inject } from '@angular/core';
 import { environment } from '@msfa-environment';
+import { ActivatedRoute, NavigationEnd, Router } from '@angular/router';
+import { filter, map, mergeMap, switchMap } from 'rxjs/operators';
+import { Title } from '@angular/platform-browser';
 
 @Component({
   selector: 'msfa-root',
@@ -9,7 +12,30 @@ import { environment } from '@msfa-environment';
   changeDetection: ChangeDetectionStrategy.OnPush,
 })
 export class AppComponent {
-  constructor(@Inject(DOCUMENT) private document: Document) {
+  constructor(
+    @Inject(DOCUMENT) private document: Document,
+    private router: Router,
+    private activatedRoute: ActivatedRoute,
+    private titleService: Title
+  ) {
     this.document.body.dataset.version = environment.version;
+
+    this.router.events
+      .pipe(
+        filter(event => event instanceof NavigationEnd),
+        map(() => traverseUntilNoChildRoute(this.activatedRoute)),
+        switchMap((route: ActivatedRoute) => route.data)
+      )
+      .subscribe((routeData: { [title: string]: string }) => {
+        const pageTitle = routeData.title;
+        this.titleService.setTitle(`${pageTitle ? `${pageTitle} - ` : ''}Mina sidor för fristående aktörer`);
+      });
   }
 }
+
+function traverseUntilNoChildRoute(route: ActivatedRoute): ActivatedRoute {
+  while (route.firstChild) {
+    route = route.firstChild;
+  }
+  return route;
+}