Refactor store observer mecanism to pilot edition actions.

src/app/app.module.ts

@@ -16,6 +16,7 @@ import {MatDialogModule} from '@angular/material/dialog';
 import {MatButtonModule} from '@angular/material/button';
 import {ReactiveFormsModule} from '@angular/forms';
 import {MatSnackBarModule} from '@angular/material/snack-bar';
+import { HeaderComponent } from './core/components/header/header.component';
 
 @NgModule({
   declarations: [
@@ -24,7 +25,8 @@ import {MatSnackBarModule} from '@angular/material/snack-bar';
     AddTaskComponent,
     DisplayTaskComponent,
     TaskListsComponent,
-    AddTaskListComponent
+    AddTaskListComponent,
+    HeaderComponent
   ],
   imports: [
     BrowserModule,