Support Helm 3.7

[eshepelyuk]

Since Helm 3.7 helm chart subcommand is removed.

Currently publish stage both creates a TGZ package and uploads it. It is more convenient to separate this functionality and create a package, ie tgz file, in prepare stage and then upload it in publish stage.

For Helm < 3.7 the new flow would be

1. Prepare is calling helm package and helm chart save
2. Publish is calling helm chart push

For Helm >= 3.7 the new flow would be

1. Prepare is calling helm package
2. Publish is calling helm push

The package location can be passed via context.