Helper API to provide metadata item for capturing provenance of a derived data file

E.g. as now came up in the context of the spike sorted data in https://github.com/dandi/dandi-cli/issues/1314 but also is to be used in the use case of @vandermeerlab (attn @TheChymera @manimoh) . I guess it should take a metadata record, original asset(s) information, and return enhanced metadata record. @satra you have mentioned that we had worked that out that somewhere.

Then with that helper in mind, we should provide documentation for https://github.com/dandi/handbook/ .