In zed1, cmd-f either opened the search buffer, or focused into it if it
was open already. Search query got updated, if any selection was made on
the moment of cmd-f call.

The PR restores that behavior and also

* fixes a bug when opened diagnostics error always got pasted
* comments out the panic on multibuffer separator click 
* removes extra stdout & stderr debug logging

Release Notes:

- N/A