Add command output options where applicable

[vdice]

Add output options for applicable terraform commands. For instance, terraform show (invoked by the status action logic in this mixin) can output in json, though note it does require a terraform client of v0.12 or later (as of writing, we use 0.11.11).

For implementation, reference https://github.com/deislabs/porter-helm/blob/master/pkg/helm/status.go