Add functionality to easily integrate with DocumentResolvers #15
Description
The existing push/pop phases will fail completely if you attempt to integrate them into a DocumentResolver pipeline. It'd be great if a simple way was provided to add similar tracing phases for such situations.
I hope to submit a PR shortly, but my absinthe knowledge is fairly limited, so feedback and discussion on this issue in the meantime would be invaluable. I also may say a number of things that are completely incorrect, so please bear with me!
For example, the existing tracer push/pop phases happen after the Absinthe.Phase.Blueprint and Absinthe.Phase.Document.Result phases. I assume the latter one will remain the same, but is there an analog to Absinthe.Phase.Blueprint when dealing with a DocumentResolver? If so, it shouldn't be overly difficult to add two new push/pop modules (or at least just push) and add an add_document_resolver_phases/1 function that does something similar.
Once that's done, all that needs to be added is a note in the readme that users' DocumentResolver modules should indeed override the pipeline/1 callback and include this new phase-adding function.
Please share any thoughts you might have! Perhaps this entire issue is misguided and I'm missing something obvious, which would actually be wonderful.
Thanks!