Update orbit selection strategy

[GriffinBabe]

At the moment, S1 orbits is being selected with the maximum accumulated area overlapping between the spatial extent and the available products in the catalogue, however this does not take into account edge cases such as:

• Long periods without any observations.
• To be filled @kvantricht

[kvantricht]

Reproduce by:

(35.85799, 49.705688, 36.039682, 49.797363)
temporal_extent = TemporalContext('2018-07-30', '2020-01-31')

chooses ascending though it has huge temporal gap at the start

[kvantricht]

#158 closes this.