[angular-16-irish-monitor]: Add rootClass subject in layout service.

(cherry picked from commit 246cafa43f)

dashboard/sharedComponents/sidebar/layout.service.ts

@@ -83,7 +83,11 @@ export class LayoutService {
    * Add hasStickyHeaderOnMobile: true in order to activate uk-sticky in header of mobile/tablet devices.
    * */
   private hasStickyHeaderOnMobileSubject: BehaviorSubject<boolean> = new BehaviorSubject<boolean>(false);
-
+  /**
+   * Add a class in root element of the html. (For different theme apply)
+   * Handle it manually in the component, it doesn't use data
+   * */
+  private rootClassSubject: BehaviorSubject<string> = new BehaviorSubject<string>(null);
   private subscriptions: any[] = [];
 
   ngOnDestroy() {
@@ -329,4 +333,12 @@ export class LayoutService {
   setHasStickyHeaderOnMobile(value: boolean) {
     this.hasStickyHeaderOnMobileSubject.next(value);
   }
+
+  get rootClass(): Observable<string> {
+    return this.rootClassSubject.asObservable();
+  }
+
+  setRootClass(value: string = null): void {
+    this.rootClassSubject.next(value);
+  }
 }