[Auth] Choose which auth storage to use based on config (#5792)

This PR is a follow-up to #5591. It allows users to choose which auth
storage mode they want by using the new
`cli_auth_credentials_store_mode` config.

codex-rs/app-server/tests/suite/user_info.rs

@@ -7,6 +7,7 @@ use app_test_support::write_chatgpt_auth;
 use codex_app_server_protocol::JSONRPCResponse;
 use codex_app_server_protocol::RequestId;
 use codex_app_server_protocol::UserInfoResponse;
+use codex_core::auth::AuthCredentialsStoreMode;
 use pretty_assertions::assert_eq;
 use tempfile::TempDir;
 use tokio::time::timeout;
@@ -22,6 +23,7 @@ async fn user_info_returns_email_from_auth_json() {
         ChatGptAuthFixture::new("access")
             .refresh_token("refresh")
             .email("user@example.com"),
+        AuthCredentialsStoreMode::File,
     )
     .expect("write chatgpt auth");