Det match updates

[mmccrackan]

May replace #1515 which is similar. This does the following:

• Adds a parameter called allow_unassigned_to_assigned which will either allow or prevent matches from bg=-1 in the design or pointing data to bg != -1 in the pointing or tuneset data. We want to prevent such matches when matching from design to pointing, since the detector types with bg=-1 should always have that value. When matching between pointing and tunesets, we allow bg = -1 to other bg values since some detectors may be assigned bg = -1 in det_cal due to the conditions of when the pointing tune was taken but may be recovered in later tunesets.
• Like Det match updates #1515, forces det_types of UNRT, SQID, and BARE to always be bg = -1.
• Prevents mismatch between assigned bgs (i.e matching bg=4 to bg=6).
• Makes det_row, det_col, and det_rhombus optional for LF.
• Adds det_match_solutions code to coords.
• Adds start_time and stop_time to update_det_match to simplify epoch handling for detsets. Future update will add epochs to the databases.