This PR adjusts the spacing of the indicator showing the number of extra
call participants that appears after the facepile:

<img width="242" alt="Screenshot 2024-01-08 at 1 09 39 PM"
src="https://github.com/zed-industries/zed/assets/1486634/6d9cbefa-3b4e-4501-ab11-51026dfb5b6c">

Release Notes:

- Added more space between the call participant facepile and the number
indicating additional call participants.