Codice continuation packets (IMAP-Science-Operations-Center#2569)

* Handling codice segmented packets
* MNT: Add logging for source sequence counters to packet decom

We have had some issues with missing source sequence counters,
meaning not all necessary packets were present. This just adds
some simple logs that can warn about this case and give some
awareness about what is going on.

* MNT: CoDICE filter out incomplete priority groups

The acquisition start times dictate what priorities are in
a group. i.e. all priorities have the same start time. Since we
know how many priorities there are per Hi/Lo configuration, we
know that we should have that many exact items with a given
acquisition start time. This allows us to filter out items that
weren't complete.

Author: greglucas