Provide enable/disable option for all resources on Helm chart

[viniciusdc]

Motivation

We at Quansight have integrated Prefect within QHub to allow for easy workflow management. Currently we are maintaining a helm chart within QHub for a prefect agent only deployment due to the Prefect provided chart not providing this option. We feel that the community as a whole would benefit from having the ability to have only the agent installed as indicated by issue https://github.com/PrefectHQ/prefect/issues/4406. We would like to contribute this chart to Prefect since this feels like a more central place for this to be managed or help the development of the helm chart to support this option. Additionally this would allow the agent only helm chart to be more easily updated with new features.

Current behavior

Currently, the Prefect server helm chart only provides an option for enabling and disabling its agent configuration but all the other components must be enabled. That's a drawback if your intention is installing the server helm chart only focuses on some of its features, or in some cases, when you need to sync it's configuration with another resource already present in your deployment.

Proposed behavior

It would be fantastic to have the ability to disable or enable all the components of the chart, not only the agent. This would grant the end user with more reliability when updating the chart, as it would be direct downloading from upstream. As well as enhance it's variety of options when deploying with already implemented features in the cluster.

Reference discussion on QHub https://github.com/Quansight/qhub/issues/819

[zanieb]

Hey @viniciusdc -- I'm a little unsure that the helm chart would be robust to disabling components as the services are a bit entangled as written. If you can propose a simple PR that adds the toggles without significant work to actually connect to existing services, I'm interested. Otherwise, it might make sense to just contribute an agent chart separately at helm/prefect-agent.