Allow indicating runtime dependencies

[entropitor]

E.g. the Kong helm chart introduces some new Custom Resource Definitions. I've built other charts on top of those CRDs but given I only want 1 kong instance but many charts declaring CRDs for this 1 kong instance, helmfile fails when I try to run it on a new cluster because it cannot find the CRD that one of the charts is declaring. It could be cool if we could say something like depends_on: ['kong'] or declares_crd: true

[mumoshu]

@entropitor Hey! Thanks for trying Helmfile. I think we already have an issue for this: #715

We'll have something like depends_on(perhaps needs: ['namespace:release']).

In the meantime, you can try sub-helmfiles as they are processed in the order of declaration.