load_stac band detection with STAC 1.1 collection

[soxofaan]

band detection of https://stac.dataspace.copernicus.eu/v1/collections/sentinel-2-l2a does not work well at the moment:

import openeo.metadata
metadata = openeo.metadata.metadata_from_stac(
    "https://stac.dataspace.copernicus.eu/v1/collections/sentinel-2-l2a",
)
print(metadata.band_names)
# shows: []

band info is in document, but client is not picking that up:

• item_assets field: client only supports that if "item_assets" extension is enabled, but that is not necessary anymore since STAC 1.1.0: https://github.com/stac-extensions/item-assets?tab=readme-ov-file#item-assets-definition-extension-specification
• bands is part of common metadata: https://github.com/radiantearth/stac-spec/blob/master/commons/common-metadata.md#bands but client does not support that at the moment

[soxofaan]

related to (or maybe even duplicate of) #692