MVP of endpoint on urn:resolver to output set of urn-to-endpoints with know expected output; use case: self test

[fititnt]

As the title says: the idea here is have at least some way to dump list of input + output + hints on output. Does not need to be perfect, just an minimal viable product.

Since the resolver is just this, a resolver, not a proxy, from time to time things will break. The way it breaks could be fault of the resolver software, network errors, or simply the place we're pointing changed it's behavior. So the idea of this issue here is not just know bugs we introduce, but have some way to know when things will break.