Now when buffer_search::Deploy action is triggered (with cmd-f), we'll
keep the previous query in query_editor (if there was one) instead of
replacing it with empty query.

This addresses this bit of feedback from Jose:
> If no text is selected, `cmd + f` should not delete the text in the
search bar when refocusing

Release Notes:
- Improved buffer search by not clearing out query editor when no text
is selected and "buffer search: deploy" (default keybind: cmd-f) is
triggered.

Reverted prior small change in inline prompting.
We should now only return code in a markdown block during inline
assists.

Begin to fix guest notifications

* Put the newest notifications at the top
* Have at most 1 notification toast, which is non-interactive,
  but focuses the notification panel on click, and auto-dismisses
  on a timer.