Delegate review to codex instance (#5572)

In this PR, I am exploring migrating task kind to an invocation of
Codex. The main reason would be getting rid off multiple
`ConversationHistory` state and streamlining our context/history
management.

This approach depends on opening a channel between the sub-codex and
codex. This channel is responsible for forwarding `interactive`
(`approvals`) and `non-interactive` events. The `task` is responsible
for handling those events.

This opens the door for implementing `codex as a tool`, replacing
`compact` and `review`, and potentially subagents.

One consideration is this code is very similar to `app-server` specially
in the approval part. If in the future we wanted an interactive
`sub-codex` we should consider using `codex-mcp`

codex-rs/core/src/codex/compact.rs

@@ -13,7 +13,6 @@ use crate::protocol::ErrorEvent;
 use crate::protocol::EventMsg;
 use crate::protocol::TaskStartedEvent;
 use crate::protocol::TurnContextItem;
-use crate::state::TaskKind;
 use crate::truncate::truncate_middle;
 use crate::util::backoff;
 use askama::Template;
@@ -255,11 +254,7 @@ async fn drain_to_completed(
     turn_context: &TurnContext,
     prompt: &Prompt,
 ) -> CodexResult<()> {
-    let mut stream = turn_context
-        .client
-        .clone()
-        .stream_with_task_kind(prompt, TaskKind::Compact)
-        .await?;
+    let mut stream = turn_context.client.clone().stream(prompt).await?;
     loop {
         let maybe_event = stream.next().await;
         let Some(event) = maybe_event else {