Add ConnectX-9 PortMetrics and TransceiverTelemetry support to D-Bus network ports

Expose PortMetrics and TransceiverTelemetry for ConnectX-9 network ports in gBMCWeb:
- Add @odata.id link to Metrics in buildNetworkPortDBus.
- Implement buildNetworkPortMetricDBus to query PortECC, PortPacketCounters, and PCIeECC from NSM D-Bus interfaces.
- Route handleNetworkPortMetricGetDBus to buildNetworkPortMetricDBus.

Tested:
Verified PortMetrics and TransceiverTelemetry endpoints return expected metric values on ConnectX-9 network ports.
Google-Bug-Id:540603557
PiperOrigin-RevId: 970680678
Change-Id: I953cf2ff8eb51e43254fa7f9efb0321d517b0dc9