[request] implement elevation data from the Norwegian Mapping Authority

Please implement the free and open elevation DTM10 data from the Norwegian Kartverket aka Norwegian Mapping Authority. The data is for Norway only.
It’s in 10x10 meter grid measurements, with a accuracy of ± 4 to 6 meters,as it’s superior to any SRTM data.
The DTM50 format is in 50x50 meter grids,same resolution. I don't know if it's possible to downgrade the size of the grids, 50x50 are the largest.

Preprocessed national dataset exports are available.
All datasets are in EUREF89, NN2000. UTM zone 33 has full coverage. Zone 32 and 35 where applicable.
The DTM10 file covering the entire Norway is 18139 MB updated 20.07.2019

DTM50 is 559 MB

The files can be found at:
https://hoydedata.no/LaserInnsyn/#downloadTab

The issue names no MAVProxy file, test, or entry point. Start by locating existing elevation-data handling and determining how the Norwegian DTM10 or DTM50 source would fit; done requires an agreed scope and verified support for the cited Norway-only datasets.

Written by the indexing model from the issue text.