This PR fixes a few issues around shutting down a debug adapter.
The first issue I discovered was when I shut down all sessions via
`shutdown all adapters` command. We would still fetch the threads
request again, because we receive a thread event that indicated that it
exited. But this will always time out because the debug adapter is
already shutdown at this point, so by updating the check so we don't
allow fetching a request when the session is terminated fixes the issue.
The second issue fixes a bug where we would always shut down the parent
session, when a child session is terminated. This was reintroduced by
the big refactor. This is not something we want, because you could
receive multiple StartDebugging reverse requests, so if one child is
shutting down that does not mean the other ones should have been
shutting down as well.
Issue was original fixed in
https://github.com/RemcoSmitsDev/zed/pull/80#issuecomment-2573943661.
## TODO:
- [x] Add tests
Release Notes:
- N/A
ac452799b0