Remove netcat dependency (#28920)

Closes #28813
Closes #27749

Release Notes:

- Removed the need to have openbsd `netcat` (`nc`) installed on your
system in order to enter passwords for `git` or `ssh` (remote
development). If you previously installed `netcat` specifically for Zed,
you may uninstall it.

crates/zed/Cargo.toml

@@ -18,6 +18,7 @@ path = "src/main.rs"
 activity_indicator.workspace = true
 agent.workspace = true
 anyhow.workspace = true
+askpass.workspace = true
 assets.workspace = true
 assistant.workspace = true
 assistant_context_editor.workspace = true