Hybrid oil heat pump in ETM

[KoenvanB]

This PR adds hybrid oil heat pumps to the ETM for households and buildings in the form of three new nodes:

• households_space_heater_hybrid_crude_oil_heatpump_air_water_electricity
• households_water_heater_hybrid_crude_oil_heatpump_air_water_electricity
• buildings_space_heater_hybrid_crude_oil_heatpump_air_water_electricity Corresponding inputs are included under the 'space heating (& hot water) section'.

Further changes include:

• Restore UKNI air temperature curve to unnormalized form (corrects a mistake)
• Queries to include oil hhps to the number_of_houses_per_space_heating_technology chart
• Queries to set the heatpump in the heat merit order.
• Queries to set the cop of the hybrid heatpump
• Queries to extract the number_of_units, cop & useable_heat

[kaskranenburgQ]

I have removed the _electricity_used_inheatpumps query since it was not used in any repositories.

[KoenvanB]

I have also updated the COP cutoffs based on the adjustments in the node source analysis.

As discussed with Mathijs, this branch is now ready to merge!