Make helm install utility accept --dry-run

[viveksinghggits]

The helm utility that we have right now https://github.com/kanisterio/kanister/blob/master/pkg/helm/client.go#L132 just installs the chart. But if there is a requirement to just generate the rendered manifests of the chart to test some templates, we can not us this method. One of such examples is #2791 (comment).

We should improve this method, so that people can configure/pass --dry-run flag to get the rendered manifests out of it. And those rendered manifests will be parsed and tested against helm values.

[github-actions]

Thanks for opening this issue 👍. The team will review it shortly.

If this is a bug report, make sure to include clear instructions how on to reproduce the problem with minimal reproducible examples, where possible. If this is a security report, please review our security policy as outlined in SECURITY.md.

If you haven't already, please take a moment to review our project's Code of Conduct document.