[REF] [Import] extract function that sets field metadata

[REF] [Import] extract function that sets field metadata

My thinking is that we want to migrate over to a new class (similar to export processor) that does a lot a metadata functions
- perhaps it might be importMetadata. A big part of the reason it's all so crazy appears to be that the functions to
wrangle the metadata are on the first class in the sequence (DataSource) and because they are not shared & do not have a shared
parent they are passed around instead via the form set &  get methods. In fact the metadata & array wrangling functions just
need to be available - hmm sounding like a trait - ok next commit....