Allow CSV validation to validate rasters/vectors referenced in a CSV column

[phargogh]

We now have several models that use CSV files to define paths to other spatial files, including HRA, HQ and CBC (once #209 is complete), and I think Recreation also does something similar.

If we want to validate a spatial filepath that is referenced in one of these inputs, the validation performed is a manual step outlined in the module's validate function. We should allow for an ARGS_SPEC-defined configuration option that then will allow for the files in a given column to be validated as a spatial file (with all of the optional validation parameters supported by the check functions).