split VIIRS into files per-satellite instead of what it is now (per-half-day)

[ghost]

currently, the VIIRS data conversion workflow combines granules from the Suomi-NPP and NOAA-20 satellites, and then splits the resulting mosaic into two files:

1. midnight (00:00:00) -> noon (12:00:00)
2. noon (12:00:00) -> midnight (24:00:00)

Instead, we would like to split this data into 2 files (1 per satellite, so it would be 3 files after #2 adds GOES-17)