[ADF-3880] fix header logo a11y (#4114)

* fix header logo a11y

* fix test

lib/core/layout/components/header/header.component.html

@@ -5,7 +5,7 @@
     </button>
 
     <a [routerLink]="redirectUrl" title="{{ tooltip }}">
-        <img src="{{logo}}" class="adf-app-logo"/>
+        <img src="{{logo}}" class="adf-app-logo" alt="{{ 'CORE.HEADER.LOGO_ARIA' | translate }}"/>
     </a>
 
     <span [routerLink]="redirectUrl" fxFlex="1 1 auto" fxShow fxHide.lt-sm="true" class="adf-app-title">{{title}}</span>

lib/core/layout/components/header/header.component.spec.ts

@@ -154,7 +154,7 @@ describe('HeaderLayoutComponent', () => {
         beforeEach(async(() => {
             TestBed.configureTestingModule({
               declarations: [HeaderLayoutTesterComponent],
-              imports: [ LayoutModule, MaterialModule, RouterTestingModule ]
+              imports: [ CoreTestingModule, LayoutModule, MaterialModule, RouterTestingModule ]
             })
             .compileComponents();
           }));

lib/core/layout/layout.module.ts

@@ -27,11 +27,13 @@ import { LayoutContainerComponent } from './components/layout-container/layout-c
 import { SidebarActionMenuComponent, SidebarMenuDirective,
     SidebarMenuExpandIconDirective, SidebarMenuTitleIconDirective } from './components/sidebar-action/sidebar-action-menu.component';
 import { HeaderLayoutComponent } from './components/header/header.component';
+import { TranslateModule } from '@ngx-translate/core';
 @NgModule({
     imports: [
         CommonModule,
         MaterialModule,
-        RouterModule
+        RouterModule,
+        TranslateModule.forChild()
     ],
     exports: [
         SidenavLayoutHeaderDirective,