ResponseBuilder should have a method accepting a map of headers

In can be tedious to manually set the cached headers on an instance of ResponseBuilder.
Response.fromResponse implementation has the code that might be reused

Start with the ResponseBuilder API and the Response.fromResponse implementation referenced in the issue. Compare how cached headers are handled there and determine the expected map-based entry point; done means callers can provide headers without setting them individually and the existing behavior remains intact.

Written by the indexing model from the issue text.