fix AF-1360
When menu (with modal = false) is rendered in Modal, the [RemoveScroll utility wrapped by Modal](660060a765/packages/react/dialog/src/Dialog.tsx (L203)) will prevent menu from scrolling.
The reason why menu is scrollable within a dialog is because it is also wrapped a RemoveScroll [when modal is on. ](660060a765/packages/react/menu/src/Menu.tsx (L305))
In this fix, added a `useWithinModal` utility hook so that menu will automatically assign noportal mode for menu when it is rendered inside of a modal.
using a [babel plugin](https://gist.github.com/pengx17/49e24ae8a5a609bdaff122ee8c679d1c) to transform all var(--affine-xxx) to cssVar
Some issues:
- tried ast-grep but it seems to be not easy to add imports conditionally
- current work does not work well with ts with types because babel will strip them out