fix: creating an instance of Codex requires a Config (#859)

I discovered that I accidentally introduced a change in
https://github.com/openai/codex/pull/829 where we load a fresh `Config`
in the middle of `codex.rs`:


c3e10e180a/codex-rs/core/src/codex.rs (L515-L522)

This is not good because the `Config` could differ from the one that has
the user's overrides specified from the CLI. Also, in unit tests, it
means the `Config` was picking up my personal settings as opposed to
using a vanilla config, which was problematic.

This PR cleans things up by moving the common case where
`Op::ConfigureSession` is derived from `Config` (originally done in
`codex_wrapper.rs`) and making it the standard way to initialize `Codex`
by putting it in `Codex::spawn()`. Note this also eliminates quite a bit
of boilerplate from the tests and relieves the caller of the
responsibility of minting out unique IDs when invoking `submit()`.

codex-rs/cli/src/proto.rs

@@ -1,7 +1,10 @@
 use std::io::IsTerminal;
+use std::sync::Arc;
 
 use clap::Parser;
 use codex_core::Codex;
+use codex_core::config::Config;
+use codex_core::config::ConfigOverrides;
 use codex_core::protocol::Submission;
 use codex_core::util::notify_on_sigint;
 use tokio::io::AsyncBufReadExt;
@@ -21,8 +24,10 @@ pub async fn run_main(_opts: ProtoCli) -> anyhow::Result<()> {
         .with_writer(std::io::stderr)
         .init();
 
+    let config = Config::load_with_overrides(ConfigOverrides::default())?;
     let ctrl_c = notify_on_sigint();
-    let codex = Codex::spawn(ctrl_c.clone())?;
+    let (codex, _init_id) = Codex::spawn(config, ctrl_c.clone()).await?;
+    let codex = Arc::new(codex);
 
     // Task that reads JSON lines from stdin and forwards to Submission Queue
     let sq_fut = {
@@ -48,7 +53,7 @@ pub async fn run_main(_opts: ProtoCli) -> anyhow::Result<()> {
                         }
                         match serde_json::from_str::<Submission>(line) {
                             Ok(sub) => {
-                                if let Err(e) = codex.submit(sub).await {
+                                if let Err(e) = codex.submit_with_id(sub).await {
                                     error!("{e:#}");
                                     break;
                                 }