Support Helm Chart in KWOK

[yuanchen8911]

It would be great if KWOK could support Helm charts. I had a brief discussion with @wzshiming on Slack, and here's a summary.

The main issue arises from the conflict with the go template's {{ and }}. Since Helm charts also use these as default values, KWOK would need to support modifying the default {{ and }}. This change is straightforward but requires modification at every occurrence.

To enable coexistence between the two, there are two options:

1. Integrate kustomize with Helm, as detailed here: https://helm.sh/docs/topics/advanced/#post-rendering
2. Integrate Helm with kustomize, as detailed here: https://kubectl.docs.kubernetes.io/references/kustomize/kustomization/helmcharts

Option 2 (integrating Helm into kustomize) appears to be the more feasible solution.

@dmitsh, what are your thoughts on this?

[yuanchen8911]

I think we should support both the original go templates and helm charts.