Set OBJECT card a bit more carefully.

We get the value of the FITS OBJECT card directly from the Gen2 PFS.OBJECT key, which is set by the PFS pfs_kansoku routines on Gen2 only when we (PFS) are running. To avoid stale values, we need to be a bit more careful.

For SPS files (PFSA/PFSB), we can use the SM's lightSource value. If it is "pfi", use PFS.OBJECT, otherwise just use the lightSource ("dcb", "dcb2", "sunss", "none"). This does depend on the Gen2 kansoku scripts updating OBJECT correctly, but that is out of our hands.

For AGCC, we should use PFS.OBJECT if any of the active lightSources are "pfi". Else we should use "unknown" for now, I think. We will eventually have a mechanism for telling that we are on the TUE system, but we don't know the details of that yet.

For MCS, we should probably use the same scheme as AGCC. Maybe use the pfsDesign if we are on the PFI? That feels wrong to me, given that we do have the design itself.