Stick REPL icon in quick action bar (#14064)

REPL Quick Actions

<img width="325" alt="image"
src="https://github.com/zed-industries/zed/assets/836375/faaf4c8f-ef12-4417-a9dd-158d5beae8ba">

When the Jupyter REPL is enabled and a kernel is available, show the
status in the editor bar:

![quick action bar
repl](https://github.com/zed-industries/zed/assets/836375/f3445283-f1fc-4714-895b-7aa842d4ab76)


Release Notes:

- N/A

---------

Co-authored-by: Nate Butler <iamnbutler@gmail.com>

docs/src/SUMMARY.md

@@ -22,6 +22,7 @@
 - [Collaboration](./collaboration.md)
 - [Tasks](./tasks.md)
 - [Remote Development](./remote-development.md)
+- [Repl](./repl.md)
 
 # Language Support