✨(react) add onSearchInputChange callback to searchable select

We want to be able to notify an event when the search term of the
searchable select gets updated.

packages/react/src/components/Forms/Select/mono-searchable.tsx

@@ -93,6 +93,10 @@ export const SelectMonoSearchable = forwardRef<SelectHandle, SubProps>(
       },
     }));
 
+    useEffect(() => {
+      props.onSearchInputChange?.({ target: { value: inputFilter } });
+    }, [inputFilter]);
+
     const onInputBlur = () => {
       setHasInputFocused(false);
       if (downshiftReturn.selectedItem) {