DataProduct model should support URL as data property #1266
Description
Currently, the data property of the DataProduct path is a django.db.fields.FileField which is gernerally used for files in local storage. This should be generalized to support URLs to data product files available anywhere. This should be independent of the data product type.
This supports a SNEx2 use-case in which DataProduct files can simply live in the LCO Data archive, but there's nothing LCO specific required -- just a URL to a Data Product file (anywhere).