Feat: Adjust the operation cell of the table on the file management page and dataset page #3221. (#7526)

### What problem does this PR solve?

Feat: Adjust the operation cell of the table on the file management page
and dataset page #3221.
### Type of change


- [x] New Feature (non-breaking change which adds functionality)

web/src/hooks/logic-hooks/use-row-selection.ts

@@ -9,11 +9,16 @@ export function useRowSelection() {
     setRowSelection({});
   }, []);
 
+  const selectedCount = useMemo(() => {
+    return Object.keys(rowSelection).length;
+  }, [rowSelection]);
+
   return {
     rowSelection,
     setRowSelection,
     rowSelectionIsEmpty: isEmpty(rowSelection),
     clearRowSelection,
+    selectedCount,
   };
 }