[ACA-4436] - added option for select item to display None (#7113)

* [ACA-4436] - added option for select item to display None

* [ACA-4436] - added unit test and fixed wrong default behaviour

* [ACA-4436] - fixed property check

* [ACA-4436] - fixed unit test

* [ACA-4436] - fixed unit test

lib/process-services-cloud/src/lib/task/task-header/components/task-header-cloud.component.ts

@@ -163,6 +163,7 @@ export class TaskHeaderCloudComponent implements OnInit, OnDestroy, OnChanges {
                     value: this.taskDetails.priority.toString(),
                     key: 'priority',
                     editable: true,
+                    displayNoneOption: false,
                     options$: of(this.taskCloudService.priorities)
                 }
             ),