Before this PR force quitting Zed would leave hanging debug adapter
processes and not allow debug adapters to clean up their sessions
properly.

This PR fixes this problem by sending a disconnect/terminate to all
debug adapters and force shutting down their processes after they
respond.

Co-authored-by: Cole Miller \<cole@zed.dev\>

Release Notes:

- debugger: Shutdown and clean up debug processes when force quitting
Zed

---------

Co-authored-by: Conrad Irwin <conrad.irwin@gmail.com>
Co-authored-by: Remco Smits <djsmits12@gmail.com>