Mapping between HSDS and VA Facilities

[mrshll1001]

Continued from openreferral/api-specification#106

The original issue is framed in terms of the API only; in reality this would likely mean mapping between the data model. There may be implications for the API Specification if systems are expected to take in particular requests, recognise them, and then make further requests to the VA Facilities API.

There would likely be guidance needed, and this also opens up the possibility of mapping to various other standards. Open Contracting achieve this quite well in a nice format, see for example OCDS for eForms which maps between OCDS and the European eForms.