feat(tabs): add isExpandEvent static method

Author: bennypowers

elements/pf-tabs/pf-tabs.ts

@@ -4,6 +4,7 @@ import { property } from 'lit/decorators/property.js';
 import { cascades } from '@patternfly/pfe-core/decorators.js';
 
 import { BaseTabs } from './BaseTabs.js';
+import { TabExpandEvent } from './BaseTab.js';
 import { PfTab } from './pf-tab.js';
 import { PfTabPanel } from './pf-tab-panel.js';
 
@@ -73,6 +74,10 @@ export class PfTabs extends BaseTabs {
     return element instanceof PfTabPanel;
   }
 
+  static isExpandEvent(event: Event): event is TabExpandEvent {
+    return event instanceof TabExpandEvent;
+  }
+
   @cascades('pf-tab', 'pf-tab-panel')
   @property({ reflect: true }) box: 'light' | 'dark' | null = null;