Ability to add additional labels to the connect serviceMonitor

[jhoblitt]

Summary

PR #151 introduced a serviceMonitor but did not include a parameter to add additional labels to the resource.

Use cases

• In my environment, we use labels on serviceMonitors to control scraping.

Proposed solution

Add support for connect.serviceMonitor.additionalLabels as is commonly supported in other charts.

Is there a workaround to accomplish this today?

The only option today is to add labels to all connect resources via connect.labels.