[ACA-3358] Show user friendly error templates when there are no applications/processDefinitions (#5746)

* * Added empty template on start process component

* * Removed errorMessageId

* * Added unit tests to recent changes

* * Added doc

* * fixed comments

* * Used showError notification

* * After rebase

* * Fixed failing e2e

* * Fixed comments

demo-shell/src/app/components/process-service/process-service.component.html

@@ -224,7 +224,8 @@
                         [name]="defaultProcessName"
                         (formContentClicked)="onContentClick($event)"
                         (start)="onStartProcessInstance($event)"
-                        (cancel)="onCancelProcessInstance()">
+                        (cancel)="onCancelProcessInstance()"
+                        (error)="onStartProcessError($event)">
                     </adf-start-process>
                 </div>
             </div>