Add skill approval event/response (#12633)

Set the stage for skill-level permission approval in addition to
command-level.

Behind a feature flag.

codex-rs/mcp-server/src/codex_tool_runner.rs

@@ -362,6 +362,7 @@ async fn run_codex_tool_session_inner(
                     | EventMsg::ExitedReviewMode(_)
                     | EventMsg::RequestUserInput(_)
                     | EventMsg::DynamicToolCallRequest(_)
+                    | EventMsg::SkillRequestApproval(_)
                     | EventMsg::ContextCompacted(_)
                     | EventMsg::ModelReroute(_)
                     | EventMsg::ThreadRolledBack(_)