Disallow running CLI with root privileges (#32583)

In #31331, I made a change that prevents Zed from running with root
privileges, but I forgot about the CLI.
So if you run the CLI without the `--foreground` flag, it just freezes
without any messages. This PR fixes that.

Release Notes:

- N/A

crates/zed/Cargo.toml

@@ -88,7 +88,7 @@ markdown_preview.workspace = true
 menu.workspace = true
 migrator.workspace = true
 mimalloc = { version = "0.1", optional = true }
-nix = { workspace = true, features = ["pthread", "signal", "user"] }
+nix = { workspace = true, features = ["pthread", "signal"] }
 node_runtime.workspace = true
 notifications.workspace = true
 outline.workspace = true

crates/zed/src/main.rs

@@ -162,22 +162,7 @@ fn fail_to_open_window(e: anyhow::Error, _cx: &mut App) {
 
 pub fn main() {
     #[cfg(unix)]
-    {
-        let is_root = nix::unistd::geteuid().is_root();
-        let allow_root = env::var("ZED_ALLOW_ROOT").is_ok_and(|val| val == "true");
-
-        // Prevent running Zed with root privileges on Unix systems unless explicitly allowed
-        if is_root && !allow_root {
-            eprintln!(
-                "\
-Error: Running Zed as root or via sudo is unsupported.
-       Doing so (even once) may subtly break things for all subsequent non-root usage of Zed.
-       It is untested and not recommended, don't complain when things break.
-       If you wish to proceed anyways, set `ZED_ALLOW_ROOT=true` in your environment."
-            );
-            process::exit(1);
-        }
-    }
+    util::prevent_root_execution();
 
     // Check if there is a pending installer
     // If there is, run the installer and exit