Render: add support for Yaml output

[scoiatael]

Plush already supports json filter.
Maybe we could extend it to add yaml and indent filters, like Helm?
Or maybe it's not needed / anti-pattern in general, so we don't want such stuff?

[bilus]

Not a bad idea, adding it should be fairly easy (I think). Working with k8s would be a good opportunity to try partials and see what would be useful for yaml rendering.