Fix #7892: CascadeSelect loading/loadingIcon typescript def (#7893)

Author: melloware

components/lib/cascadeselect/cascadeselect.d.ts

@@ -281,6 +281,15 @@ export interface CascadeSelectProps extends Omit<React.DetailedHTMLProps<React.I
      * @defaultValue 400px
      */
     scrollHeight?: string | undefined;
+    /**
+     * Display loading icon.
+     * @defaultValue false
+     */
+    loading?: boolean | undefined;
+    /**
+     * Name of the loading icon or JSX.Element for loading icon.
+     */
+    loadingIcon?: IconType<CascadeSelectProps> | undefined;
     /**
      * Callback to invoke on value change
      * @param {CascadeSelectChangeEvent} event - Custom change event