[MCP] Add auth status to MCP servers (#4918)

This adds a queryable auth status for MCP servers which is useful:
1. To determine whether a streamable HTTP server supports auth or not
based on whether or not it supports RFC 8414-3.2
2. Allow us to build a better user experience on top of MCP status

codex-rs/Cargo.lock

@@ -1352,6 +1352,7 @@ version = "0.0.0"
 dependencies = [
  "anyhow",
  "axum",
+ "codex-protocol",
  "dirs",
  "futures",
  "keyring",