Add system fields to data_entity table

[damirabdul]

trafficstars

We have created_at and updated_at fields in data_entity table, which are holding values, which came from collectors. However, in all other tables these fields are system fields and holding info about when row appears in our database.

Need to add additional fields, e.g. external_created_at and external_updated_at at fill them with external values and use created_at and updated_at fields for internal updates