Add `CreateResult` to `NewFilter` and absorb field mapping
The original version of `Filter` classes had a helper header file named `CreateResult.h` that had several forms of a `CreateResult` function that helped correctly create the `DataSet` to be returned from a filter's `DoExecute`. With the move to the `NewFilter` structure, these functions did not line up very well with how `DataSet`s should actually be created. A replacement for these functions have been added as protected helper methods to `NewFilter` and `NewFilterField`. In addition to moving them into the filter themselves, the behavior of `CreateResult` has been merged with the map field to output functionality. The original implementation of `Filter` did this mapping internally in a different step. The first design of `NewFilter` required the filter implementer to call a `MapFieldsOntoOutput` themselves. This new implementation wraps the functionality of `CreateResult` and `MapFieldsOntoOutput` together so that the `DataSet` will be created correctly with a single call to `CreateResult`. This makes it easier to correctly create the output.
create-result-does-field-map6 jobs for