Fix --user-data-dir (#44235)

Closes #40067

Release Notes:

- The `--user-data-dir` flag now works on Windows and Linux, as well as
macOS if you pass `--foreground`.

---------

Co-authored-by: Lukas Wirth <me@lukaswirth.dev>

crates/zed/src/main.rs

@@ -3,7 +3,7 @@ mod zed;
 
 use agent_ui::AgentPanel;
 use anyhow::{Context as _, Error, Result};
-use clap::{Parser, command};
+use clap::Parser;
 use cli::FORCE_CLI_MODE_ENV_VAR_NAME;
 use client::{Client, ProxySettings, UserStore, parse_zed_link};
 use collab_ui::channel_view::ChannelView;