[types] per-value factory function

[nandorojo]

Currently, this usage doesn't have proper types for factory functions:

<View 
  sx={{ p: theme => theme.space.$2 }}
/>

This usage does have the correct types, on the other hand:

<View 
  sx={theme => ({ p: theme.space.$2 })}
/>

However, this isn't good enough for many use-cases. If you want to create a wrapper component that spreads its sx styles directly on the props, then you can't use the sx prop with a theme:

import { Sx, View } from 'dripsy'
const Box = ({ children, ...sx }: React.PropsWithChildren<Sx>) => <View sx={sx}>{children}</View>

// theme isn't properly typed
<Box p={theme => theme.space.$3} />

[nandorojo]

Opened a PR to fix this: #166