Factor out telescope and environmental conditions into new table(s)

This has cropped up in a couple of places. SPS, MCS, and AGC variously need to know the telescope positions (alt/az/rot/adc/focus/etc), the environmental conditions (temperature/humidity/etc), and the observing conditions (seeing, cloud conditions, etc). All of this comes from Gen2, via the gen2Actor.

As it stands, the mcs_exposure and tel_condition tables and the MCS and SPS headers have some/all of this information, all populated from the gen2 MHS keywords, which are direct copies of the gen2 keywords.

Can we create system-independent tables just for these properties, and have the appropriate mcs, arc, and sps tables link to them? The gen2Actor can easily add rows periodically and/or at roughly the right times for each system's exposures, and can certainly create one row per MCS/AGC/SPS integration or readout (thinking about H4s and AGC here).

I do not know about the timing properties of the telescope or environmental info in the gen2 keywords – there is no point in doing better than that. On the PFS side, the H4/AGC cadence (one per 5-10s) is the fastest we would ever care about. eric?

tel_condition is empty, so we can rethink that completely.
I think two tables (telescope and everything else), but one would also work and be nicer for queries. Or also split out the human-generated conditions into its own table?