update the template to declare the input args as a struct type

[hcliff]

instead of redefining a struct repeatedly create a type to declare the input args.

My motivation was to allow me to make assertions on this call in my tests (ginkgo/gomega in the example below) without needing to redeclare the struct myself

Eventually(func() []listservicesstub.PersistListsCall {
  return elasticStub.PersistListsCalls()
}).Should(ConsistOf(listservicesstub.PersistListsCall{
  Lists: []models.List{newList},
}))

100% backwards compatible and actually results in less generated code

[hcliff]

any thoughts about this? would love to get it merged

[matryer]

Could we have this on two lines? I'm not a fan of compressing code onto one line at the cost of readability?

[matryer]

How much noise does this add to the API?

[matryer]

Hey @hcliff - thank you so much for this. I wonder if the additional types in the package space end up cluttering it too much? What do you think?