Fix cursor shape flickering and dead-zone on 1px border around list items in project and outline panels (#20202)

Move click listener to outer div
- Avoids dead area when clicking the 1px border around a list item
- Avoids flickering cursor shape when moving the cursor above the list,
and especially when scrolling the list with a stationary cursor.

Closes #15614

Release Notes:

- Fixed mouse cursor shape flickering in project and outline panels when
crossing items
([#15614](https://github.com/zed-industries/zed/issues/15614))

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Co-authored-by: Stephan Aßmus <stephan.assmus@sap.com>