fix: leverage codex_utils_cargo_bin() in codex-rs/core/tests/suite (#8887)

This eliminates our dependency on the `escargot` crate and better
prepares us for Bazel builds: https://github.com/openai/codex/pull/8875.

codex-rs/core/tests/common/lib.rs

@@ -1,5 +1,6 @@
 #![expect(clippy::expect_used)]
 
+use codex_utils_cargo_bin::CargoBinError;
 use codex_utils_cargo_bin::find_resource;
 use tempfile::TempDir;
 
@@ -245,6 +246,10 @@ pub fn format_with_current_shell_display_non_login(command: &str) -> String {
         .expect("serialize current shell command without login")
 }
 
+pub fn stdio_server_bin() -> Result<String, CargoBinError> {
+    codex_utils_cargo_bin::cargo_bin("test_stdio_server").map(|p| p.to_string_lossy().to_string())
+}
+
 pub mod fs_wait {
     use anyhow::Result;
     use anyhow::anyhow;