Remove/consolidate utility functions

[greglucas]

Summary

#687 consolidated a few previous utility functions into one common function that can be used across the instruments.

Specifically, sort_by_time and group_by_apid could be removed and we can rely upon the combined function instead.

Requirements

Replace usages of these two utility functions where appropriate.

Instruments that use group_by_apid (some in only the test suite):

• codice
• hit - HIT: Refactor hit_l1a.py to use packet_file_to_datasets function #822
• swapi - MNT/TST: Update SWAPI packet definition and tests #803
• swe - WIP/MNT: Update SWE to use packet_file_to_datasets #802
• ultra

Instruments that use sort_by_time:

• codice
• hit
• swe - WIP/MNT: Update SWE to use packet_file_to_datasets #802
• ultra

Related tickets

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