[Feature] Allow packing/unpacking into an ordered representation

[daidoji]

Background

We are working on a cryptographic encoding scheme that relies on the ordering of map key/values when serializing and deserializing to ensure the cryptographic properties of the various crypto matter (signatures, digests, hashes, etc...) verify correctly in the suite of schemes.

Feature Description

Allow the packing/unpacking into ordered representations equivalent to the serialization/deserialization order. This would be similar to https://hexdocs.pm/jason/Jason.OrderedObject.html for Jason or for a message pack example where msgpack-erlang can serialize/deserialize into ordered list representations in jiffy/jsx.

This would be really great and provide a needed feature to people developing these types of applications in the future.