Add new simulation path, allowing reprocessing into alternate DB.

We would like to reprocess existing PFSC files, along with the db inputs which were available when they were first reduced. But we want the new outputs – mcs_data, cobra_match, etc to be saved to an alternate DB for comparison with original or other reductions.

We just need to be able to switch the database and to tighten up the loading of existing files/rows.

This has been implemented well enough to get through a new expose object rerunFrameId=NNN doCentroid command and populate mcs_data using the shadow DB in Hilo (which is accessible from the summit). This can be run from a running mcsActor, after re-homing the database with, say, setDb hostname=pfsa-db01-gb.subaru.nao.ac.jp port=5434 db=mcs_test_01

There are some remaining sql/db issues, addressed in another ticket.