Chart[Network Node]: Add support for rendering an optional PrometheusOperator ServiceMonitor resource definition

[nathanklick]

User Story

As an engineer,

I need

to capture metrics from the node software and other components which support a Hedera network deployment.

So that

I can reliably determine the operational state of the network and make a pass/fail determination for a given test.

Requirements

• Implement an optional ServiceMonitor definition for the network node container gated by a boolean flag defined as a chart value.
  • https://github.com/prometheus-operator/prometheus-operator/blob/main/Documentation/user-guides/running-exporters.md#servicemonitors
• There should only be a single ServiceMonitor which handles all network node pods using a label selector.