Add REPL dropdown menu to toolbar (#14493)

TODO: 


- [x] Actions run from menu not firing
- [x] Menu differentiates idle and busy for running kernel

Menu States:
- [x] No session && no support known

No session && no kernel installed for languages of known support
- (TODO after) Intro to REPL
- [x] Link to docs

No session but can start one
- [x] Start REPL
- (TODO after) More info -> Docs?

Yes Session

- [x] Info: Kernel name, language
  example: chatlab-3.7-adsf87fsa (Python)
  example: condapy-3.7 (Python)
- [x] Change Kernel -> https://zed.dev/docs/repl#change-kernel
- ---
- [x] Run
- [x] Interrupt
- [x] Clear Outputs
- ---
- [x] Shutdown


(Release notes left empty as the change will be documented in the REPL
release!)

Reserved for a follow on PR:

```
- [ ] Status should update when the menu is open (missing `cx.notify`?)
- [ ] Shutdown all kernels action
- [ ] Restart action
- [ ] [Default kernel changed - restart (this kernel) to apply] // todo!(kyle): need some kind of state thing that says if this has happened
```


Release Notes:

- N/A

---------

Co-authored-by: Marshall Bowers <elliott.codes@gmail.com>
Co-authored-by: Kyle Kelley <rgbkrk@gmail.com>
Co-authored-by: Piotr Osiewicz <24362066+osiewicz@users.noreply.github.com>