Add role="alert" to callouts only when enforceAlert is passed (#528)

* Add role="alert" to callouts when enforceAlert is passed

* Remove ElementRef and do a different way

* Rename input variable

angular/src/components/callout.component.ts

@@ -19,6 +19,7 @@ export class CalloutComponent implements OnInit {
     @Input() clickable: boolean;
     @Input() enforcedPolicyOptions: MasterPasswordPolicyOptions;
     @Input() enforcedPolicyMessage: string;
+    @Input() useAlertRole = false;
 
     calloutStyle: string;