Add metadata file to Sentinel2 test data gen

[adriantre]

This will make testing in #2903 much simpler.

Temporarily storing raster bounds as footprint in the metadata file. To compute the actual valid footprint it will need the new method get_valid_footprint_from_datasourcein the above mentioned PR.

Fixes an error in the raster definition, see comment below.

• [ ] Add altered raster files and new metadata file to git (required to merge?)

Plot of 10m, 20m, 60m bands and computed footprint in WGS84 (using get_valid_footprint_from_datasource)