Feature Request: add the ability to add provenance to each component of proofing

Feature Request: add the ability to add provenance to each component of proofing (origin/via/destination/forward connection)

Use-case: there is different types of evidence available for parts of populations. Sometimes we know explicitly where a population projects. but not the entire path. We would like to be able to attach the provenance, and have the ability to export that to be visible to the public / SCKAN.

No files, tests, or entry points are named. Start by tracing how proofing components—origin, via, destination, and forward connection—are represented and exported, then define how provenance should attach to partial paths and appear in public or SCKAN output.

Written by the indexing model from the issue text.