Add 'slantRangeDistance' in geometryGeo.h5 for mintpy

[manudeo]

For some workflows in Mintpy, a slant range distance is required. It would be great if this could be added while preparing the mintpy input files. Something like this in prep_mintpy.py works:

from mintpy.utils.utils0 import incidence_angle2slant_range_distance

And after incidence angle calculation:

dsDict["slantRangeDistance"] = incidence_angle2slant_range_distance(meta, incidence_angle)

Thanks.