ETL insertions improvement: allow multiple insertions of gas stations

[jcalvarezj]

As discussed with the backend team, an improvement necessary for the ETL module is to be able to inject records multiple times for the gasoline stations table. The goal is to update already existing records and insert new ones.

Considerations to have:

• The primary key for records will be an incremental UID, so the station id code should not be used for that purpose anymore
• The station can be identified by its register field (permission code unique to that station)
• Remember that the field status should be ghost by default and is_active true