Add the hourly billing agent ubbagent to our helm chart

[maelvls]

Requirement: #7 must have been done.

This issue is about adding the image we built in #7 to our Helm chart.

The marketplace documentation billing-integration.md and the ubbagent README.md propose adding the agent as a container to the application's deployment.

Note: right now, we don't care about anti-cheating; we just want the ubb-image to report to the Google Billing API the hourly use of the jetstack-secure-for-cert-manager solution when it is being run by a customer.