Chat: extend Message type with a custom property (DevExpress#29809)

Author: Zedwag

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

@@ -230,6 +230,8 @@ export type Message = {
      * @public
      */
     isDeleted?: boolean;
+
+    [key: string]: any;
 };
 
 /** @public */

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

@@ -33363,6 +33363,8 @@ declare module DevExpress.ui.dxChat {
      * [descr:Message.isDeleted]
      */
     isDeleted?: boolean;
+
+    [key: string]: any;
   };
   /**
    * [descr:User]