chore: make create_approval_requirement_for_command an async fn (#7501)

I think this might help with https://github.com/openai/codex/pull/7033
because `create_approval_requirement_for_command()` will soon need
access to `Session.state`, which is a `tokio::sync::Mutex` that needs to
be accessed via `async`.

codex-rs/core/src/tools/handlers/shell.rs

@@ -231,6 +231,15 @@ impl ShellHandler {
         let event_ctx = ToolEventCtx::new(session.as_ref(), turn.as_ref(), &call_id, None);
         emitter.begin(event_ctx).await;
 
+        let approval_requirement = create_approval_requirement_for_command(
+            &turn.exec_policy,
+            &exec_params.command,
+            turn.approval_policy,
+            &turn.sandbox_policy,
+            SandboxPermissions::from(exec_params.with_escalated_permissions.unwrap_or(false)),
+        )
+        .await;
+
         let req = ShellRequest {
             command: exec_params.command.clone(),
             cwd: exec_params.cwd.clone(),
@@ -238,13 +247,7 @@ impl ShellHandler {
             env: exec_params.env.clone(),
             with_escalated_permissions: exec_params.with_escalated_permissions,
             justification: exec_params.justification.clone(),
-            approval_requirement: create_approval_requirement_for_command(
-                &turn.exec_policy,
-                &exec_params.command,
-                turn.approval_policy,
-                &turn.sandbox_policy,
-                SandboxPermissions::from(exec_params.with_escalated_permissions.unwrap_or(false)),
-            ),
+            approval_requirement,
         };
         let mut orchestrator = ToolOrchestrator::new();
         let mut runtime = ShellRuntime::new();