Add grid_mapping to output of regridding stages

[niallmcc]

https://github.com/surftemp/gbcs/issues/1246#issuecomment-2270752512

From @oembury

Adding the auxiliary data (dem, land/sea mask etc) to the Level 1c in the gbcs pre-processor step would require the Level 1c to store the full projection information (i.e. retain the grid_mapping variable) so that we can ensure that the correct data is used. The current landsat L1c does not record the grid_mapping so we can not tell if a l1c input is on the CHUK grid, greenland, or some other projection.

This may require updates to landsat_importer (to record original landsat UTM grid); eo-pipelines?; and the regridding tool

This issue is copied from surftemp/eo-pipelines#1

I have created a new regridder project based on one of the various regridders in eo-pipelines. However, this needs proper testing and documentation.

[niallmcc]

This regridder is fairly flexible other than requiring that the destination grid is a regular grid and the source and target CRS are known. I am hopeful that this could be a good regridder to standardise on, once it has been through some testing.