Sentinel-2 Importer Improvemente: importing S-2 data from region an time without any ID

[anikaweinmann]

From #295 some TODOs are open one of these is the implementation of importing S-2 data from region an time without any ID:
implement query such that all S2 data from region and time of interest are imported (e.g. using i.sentinel.coverage + t.sentinel.import). This is currently implemented with the BigQuery approach and should be replaced.