[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/cli/tests/mcp_list.rs

@@ -55,7 +55,9 @@ fn list_and_get_render_expected_output() -> Result<()> {
     assert!(stdout.contains("docs-server"));
     assert!(stdout.contains("TOKEN=secret"));
     assert!(stdout.contains("Status"));
+    assert!(stdout.contains("Auth"));
     assert!(stdout.contains("enabled"));
+    assert!(stdout.contains("Unsupported"));
 
     let mut list_json_cmd = codex_command(codex_home.path())?;
     let json_output = list_json_cmd.args(["mcp", "list", "--json"]).output()?;
@@ -80,7 +82,8 @@ fn list_and_get_render_expected_output() -> Result<()> {
               }
             },
             "startup_timeout_sec": null,
-            "tool_timeout_sec": null
+            "tool_timeout_sec": null,
+            "auth_status": "unsupported"
           }
         ]
         )