Had a user state that they didn't know how to enable vim mode and that
it was "almost a non-starter" for them. IMO, it is a big enough feature
to warrant being on the welcome screen.

<img width="968" alt="SCR-20231008-rnhj"
src="https://github.com/zed-industries/zed/assets/19867440/a189c646-1fa7-497c-b6d9-37cb1caa0492">

Release Notes:

- Added an `Enable vim mode` checkbox to the welcome screen