support MCP elicitations (#6947)

No support for request schema yet, but we'll at least show the message
and allow accept/decline.

<img width="823" height="551" alt="Screenshot 2025-11-21 at 2 44 05 PM"
src="https://github.com/user-attachments/assets/6fbb892d-ca12-4765-921e-9ac4b217534d"
/>

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

@@ -208,6 +208,10 @@ async fn run_codex_tool_session_inner(
                     EventMsg::Warning(_) => {
                         continue;
                     }
+                    EventMsg::ElicitationRequest(_) => {
+                        // TODO: forward elicitation requests to the client?
+                        continue;
+                    }
                     EventMsg::ApplyPatchApprovalRequest(ApplyPatchApprovalRequestEvent {
                         call_id,
                         turn_id: _,