Support new STAC "bands" construct

[soxofaan]

see

• [RFC] A common construct to replace `raster:bands` and `eo:bands` radiantearth/stac-spec#1213
• Bands RFC #1213 radiantearth/stac-spec#1254

We currently support "eo:bands" and "raster:bands" metadata in a couple of places in python driver, and we should prepare now to add this future "bands" construct too

[soxofaan]

On related note: in the python client there is also a growing body of STAC metadata handling logic, and I think we should avoid this kind of duplication between python client and driver, e.g. to more easily support future STAC features

[JeroenVerstraelen]

Open-EO/openeo-geopyspark-driver#762

[soxofaan]

related:

• Capabilities doc: bump to STAC 1.x? #363

common "bands" is a STAC 1.1 feature, so we would also have to make sure the general STAC version is handled properly (or at least pragmatically)