[ADF-2859] conditional evaluation of disabled state for content actions (#3450)

* react on [disabled] binding changes

* [disabled] binding updates for context menu items

* evaluating disabled state with a function

* unit test

* restore original description

* remove irrelevant test

* fix tests

demo-shell/src/app/components/files/files.component.ts

@@ -542,4 +542,15 @@ export class FilesComponent implements OnInit, OnChanges, OnDestroy {
             }
         }
     }
+
+    isCustomActionDisabled = (node: MinimalNodeEntity): boolean => {
+        if (node && node.entry && node.entry.name === 'custom') {
+            return false;
+        }
+        return true;
+    }
+
+    runCustomAction(event) {
+        console.log(event);
+    }
 }