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.

Cargo.lock

@@ -448,7 +448,6 @@ dependencies = [
  "smol",
  "tempfile",
  "util",
- "which 6.0.3",
  "workspace-hack",
 ]
 
@@ -11752,6 +11751,7 @@ name = "remote_server"
 version = "0.1.0"
 dependencies = [
  "anyhow",
+ "askpass",
  "async-watch",
  "backtrace",
  "cargo_toml",
@@ -18204,6 +18204,7 @@ dependencies = [
  "agent",
  "anyhow",
  "ashpd",
+ "askpass",
  "assets",
  "assistant",
  "assistant_context_editor",