[elicitations] Switch to use MCP style elicitation payload for mcp tool approvals. (#13621)

- [x] Switch to use MCP style elicitation payload for mcp tool
approvals.
- [ ] TODO: Update the UI to support the full spec.

codex-rs/rmcp-client/tests/resources.rs

@@ -73,6 +73,7 @@ async fn rmcp_client_can_list_and_read_resources() -> anyhow::Result<()> {
                     Ok(ElicitationResponse {
                         action: ElicitationAction::Accept,
                         content: Some(json!({})),
+                        meta: None,
                     })
                 }
                 .boxed()