Add small-scale wind & update solar PV and industry efficiency sliders

[KoenvanB]

This pull request contains three adjustments of and additions to the front-end:

1. Update industry efficiency input statements to 'overall efficiency improvement' instead of 'efficiency improvement/year';
2. Change solar PV capacity input statements to MW instead of '% of rooftop area potential';
3. Add a 'land use of solar and wind' visual to the front end, including input statements to distribute existing onshore inland wind capacity between large-scale and small-scale turbines.

Additionally, as a part of feature 3, the households_water_heater_solar_thermal.converter node has been updated with data from a new NSA.

Issues to check:

• [ ] Are the ETFlex queries etflex_households_solar_pv_installed and etflex_score_deviations_from_reference_scenario correctly updated?

Closes #2591

[mabijkerk]

Update industry efficiency input statements to 'overall efficiency improvement' instead of 'efficiency improvement/year';

All these changes require an accompanying migration that sets existing inputs to updated or new inputs.

[mabijkerk]

Change solar PV capacity input statements to MW instead of '% of rooftop area potential';

This changes also require a migration.

[mabijkerk]

Two main issues stand out for me with the small and large wind turbines. First, the full load hours of the small-scale wind turbines is higher than those of large scale wind turbines. This seems counter-intuitive to me, as I would expect larger wind turbines to benefit from higher wind speeds at hub height. See screenshot below.

Second, by allocating part of the installed capacity for wind turbines to small scale and large scale, but then using a new amount of full load hours for the small scale, the total amount of electricity generated by wind turbines in land does not add up. For example, in a blank nl2019 scenario with 50/50 large and small, I get the following electricity production:

This sums to 5410 GWh. But if I then just query the original amount of electricity produced by wind turbines in land, I get 2412 MW times 2070 flh, so roughly 5010 GWh. For me this seems counter-intuitive: I would expect the amount of electricity produced by small and large scale wind turbines to sum to the total amount of electricity produced by in land wind turbines.