Add support for helm post-rendering patches

[gberche-orange]

Expected behavior

As a helm-kubectl-boshrelease author

• in order to patch the content of an helm chart (e.g. while an upstream issue/request is being handled)
• I need support for ready to use helm post-rendering hooks such as kustomize

Observed behavior

The helm action indeed supports custom options to helm command suiteable for running the --post-renderer option

$ helm install mychart stable/wordpress --post-renderer ./path/to/executable

However, sharing the ./path/to/executableand kustomize binary among deployments might be desirable to avoid duplications

References

• https://austindewey.com/2020/07/27/patch-any-helm-chart-template-using-a-kustomize-post-renderer/
• https://helm.sh/docs/topics/advanced/ Helm post-rendering support introduced in Helm 3.1+