Direct emissions import of Dutch regional emissions.csv from regional data pipeline - #3465

Ready for final review by @mabijkerk

I haven't had the time to look into these PRs. One thing that I did not already is the role and data pipeline for 1.A.3.e (Other transportation). It requires further investigation. I had AI summarise some of the discussion:

Flag for review: possible double counting of 1.A.3.e (Other transportation).
In ETSource, transport_non_specified is mapped to CRT code 1.A.3 (all of transport), while other_other_transportation is a separate 1.A.3.e subsector. Both are in the direct_emissions group and both are summed. In ETDataset-public, the ETLocal key energetic_emissions_other_ghg_transport takes the full 1.A.3 total (greenhouse_gas_emissions.xlsx, Sectors!O16) and does not subtract 1.A.3.e. The NL municipal mapping (all_ghg_mapping.csv) also assigns gas transport N₂O (1.A.3.e.i) to that transport key. As a result, any regional dataset that also gets a value for other_other_transportation will count 1.A.3.e twice. For the country emissions.csv files, 1.A.3.e matches the EEA data exactly, but the transport value matches neither full 1.A.3 nor 1.A.3 minus 1.A.3.e. Someone needs to check in the pipeline whether 1.A.3.e is subtracted from transport.