Describe the feature you'd like to see

As we begin to delve into country specific validation we will need to implement country specific technology costs and when data is not available, at least implement region technology costs.

This is already being done in other open-source projects like osemosys-global as seen here --> https://github.com/transition-zero/feo-esmod-osemosys/blob/master/resources/data/weo_2020_powerplant_costs.csv

It would involve adding an iso2 index to the technology data as mentioned here -> PyPSA/technology-data#63

We could then pull technology data based on the countries defined in the config file and use regional defaults like the ones in config_osm_data when country specific ones are not available.

FYI the IEA has regional technology-data that could be used for the defaults and I am aware of at least 2-3 sources for country specific costs in the ASEAN region.