feat(install): add Helm chart for Operator installation

[Prasunamadasu]

As discussed in issue #1140, this PR introduces the initial version of the custom Helm chart for deploying the Cryostat operator.

[andrewazores]

Hi @Prasunamadasu , sorry for such a delayed response here - I was away on vacation, and since getting back we've been busy with wrapping up Cryostat 4.1 and preparing for the release. I'll circle back to this in the near future.

[andrewazores]

This looks very cool, and thanks for also including the GitHub Actions YAML definition.

A few general thoughts:

• this will need to be adjusted to deploy latest/snapshot/dev builds of the various operand container images rather than 3.0, and in release branches it'll get updated to deploy builds from the appropriate branches/tags (same as how the Operator and the mainline Helm chart do)
• it'd be nice if some of these Helm templates could be generated from Operator manifest bases, or vice-versa. For example, the Helm template for the Cryostat CRD could probably be copied from or at least partially generated from the Operator CRD base, which would save some maintenance effort and reduce the risk of missing changes/updates.

[andrewazores]

This produces a certmanager-related complaint:

$ helm install cryostat-operator . --create-namespace -n cryostat-operator
Error: INSTALLATION FAILED: template: cryostat-operator/templates/secret.yaml:21:20: executing "cryostat-operator/templates/secret.yaml" at <.Values.certManager.issuer.kind>: nil pointer evaluating interface {}.kind

values.yaml doesn't seem to have certManager.issuer for any default values, so either this should be included in the values.yaml or the installation instructions should describe the prerequisite setup steps.