Update `Autocomplete.Overlay` props API

[colebemis]

Problem

The API for passing props to the Autocomplete.Overlay component is unintuitive. For example, to change the width of the overlay, you need to pass width to a prop called overlayProps

<Autocomplete.Overlay overlayProps={{width: 'medium'}}>

https://primer.style/react/Autocomplete

Solution

I would expect to be able to pass overlay props directly to the Autocomplete.Overlay component:

<Autocomplete.Overlay width="medium"/>

cc @mperrotti