Provide overload of wrap_results that does not need a result_map

PropertyType<T>::wrap_results takes two arguments the results map that it is adding the results to and the results to add to the map. The motivation for taking the results map is that it supports concatenation of multiple property types' results into a single result map; however, when there is only a single property type (or equivalently it's the call to the first of several property types) this leads to code like auto rv = results() to make the initial result map. We should create an overload of wrap_results that does not require a results_map.

Note: this will likely require SFINAE to pull off as the resulting signature will be fully templated.

Start at the PropertyType::wrap_results entry point and inspect its current callers, especially those that create an initial results() map. Determine how the templated overload can coexist with the existing concatenation form, including the noted SFINAE constraint. Done means a single property type can call wrap_results without supplying a result map while existing multi-property behavior remains supported.