I have a case where I render items which have optional subtext (see example below). In the case where the subtext is not available I'd like to show a smaller sized menu item. Currently, `FixedSizeList` [is used](https://github.com/based-ghost/react-functional-select/blob/master/src/components/Menu/MenuList.tsx#L4), which doesn't support this behaviour. Could `VariableSizeList` [be used instead](https://react-window.vercel.app/#/examples/list/variable-size)? 