Sampling Copernicus DEM

[scottyhq]

I think it would be useful to add the Copernicus DEM as a raster dataset that can be sampled:
(https://github.com/SlideRuleEarth/sliderule/blob/main/packages/core/extensions/earth_data_query.lua)

This VRT is references the original data with geoid heights:
https://opentopography.s3.sdsc.edu/raster/COP30/COP30_hh.vrt

The recommended PROJ pipeline to transform to EPSG:7912 (https://uw-cryo.github.io/3D_CRS_Transformation_Resources/cop30/) is

+proj=pipeline
      +step +proj=axisswap +order=2,1
      +step +proj=unitconvert +xy_in=deg +xy_out=rad
      +step +proj=vgridshift +grids=us_nga_egm08_25.tif +multiplier=1
      +step +proj=cart +ellps=WGS84
      +step +proj=helmert +x=-0.0024 +y=0.0016 +z=0.0232 +rx=-0.00027 +ry=0.00027
            +rz=-0.00038 +s=0.00208 +dx=-0.0001 +dy=-0.0001 +dz=0.0018 +drx=0 +dry=0
            +drz=0 +ds=-8e-05 +t_epoch=2005 +convention=coordinate_frame
      +step +inv +proj=cart +ellps=WGS84
      +step +proj=unitconvert +xy_in=rad +xy_out=deg
      +step +proj=axisswap +order=2,1

cc @bessoh2