`load_stac`: possible improvements

[clausmichele]

Currently load_stac relies on the stackstac library, which works fine until we try to load more complex types of STAC objects.

As far as I am aware, current limitations of stackstac are:

• Can load only single band COGs: multi-band geoTIFFs are not supported
• Can't load STAC based on netCDF data
• Always load the data as Float64: Use data_type and nodata from raster extension if present gjoseph92/stackstac#91
• Can produce a shift in the data: Stackstac.stack provides shifted pixel coordinnates compare to qgis/rioxarray gjoseph92/stackstac#207

This limits the functionality of the implemented process. I will investigate the possible switch to either:

• odc-stac: regularly maintained and updated
  • Currently doesn't handle scale and offset automatically: Scale/offset with raster:bands.{scale|offset} opendatacube/odc-stac#55
• xpystac: based on both stackstac and odc-stac

WIP here: https://github.com/clausmichele/openeo-processes-dask/tree/feature/load_stac_odc