TabPanel: add itemIndex to the TitleClickEvent typescript definition (T1296996) (#30258)

Author: EugeniyKiyashko

packages/devextreme/js/ui/tab_panel.d.ts

@@ -49,6 +49,8 @@ export interface TabPanelItemInfo<TItem extends ItemLike> {
     readonly itemData?: TItem;
     /** @docid */
     readonly itemElement?: DxElement;
+    /** @docid */
+    readonly itemIndex: number;
 }
 
 /**
@@ -355,7 +357,7 @@ export type Options<
     TKey = any,
 > = Properties<TItem, TKey>;
 
-///#DEBUG
+/// #DEBUG
 // eslint-disable-next-line import/first
 import { CheckedEvents } from '../core';
 
@@ -419,4 +421,4 @@ onSelectionChanging?: ((e: SelectionChangingEvent) => void);
  */
 onSelectionChanged?: ((e: SelectionChangedEvent) => void);
 };
-///#ENDDEBUG
+/// #ENDDEBUG

packages/devextreme/ts/dx.all.d.ts

@@ -26758,6 +26758,10 @@ declare module DevExpress.ui {
        * [descr:TabPanelItemInfo.itemElement]
        */
       readonly itemElement?: DevExpress.core.DxElement;
+      /**
+       * [descr:TabPanelItemInfo.itemIndex]
+       */
+      readonly itemIndex: number;
     }
     /**
      * [descr:_ui_tab_panel_TitleClickEvent]