Extract MCP binding clients from the connection manager (#34561)

## What changed

- Add `McpBindingClients` to hold the ready MCP clients captured for a model step.
- Move concurrent, paginated resource and resource-template listing into the new helper.
- Keep server filtering in `McpConnectionManager` while preserving per-client timeouts, duplicate-cursor detection, and warning behavior.

GitOrigin-RevId: 0e3f8f135126b17d73058ca84e98493a27543ca0

codex-rs/codex-mcp/src/lib.rs

@@ -82,6 +82,7 @@ pub use mcp::mcp_permission_prompt_is_auto_approved;
 pub use mcp::qualified_mcp_tool_name_prefix;
 
 pub(crate) mod auth_elicitation;
+pub(crate) mod binding_clients;
 mod catalog;
 pub(crate) mod codex_apps;
 pub(crate) mod connection_manager;