Please add information about broken cobras to pfsDesign files

We need to track broken cobras in the reductions (as e.g. we cannot get good fibre profiles). They will probably mostly be UNASSIGNED, but maybe sometimes usable as SKY. Note that broken cobras with broken (or cut?) fibres are already marked as BROKENFIBER and that this ticket is about fibres that don't move properly, but which carry good fibres.

There are three cases: both axes (theta and phi) are broken so the cobra cannot move, and those with one broken motor, either theta or phi. The latter can be moved away from stars, while the former can happen to lie near bright stars or galaxies.

It's tempting to simply add BROKENCOBRA, BROKENCOBRA_PHI, and BROKEN_COBRA_THETA to pfsDesign.fiberStatus, and I think that this is probably the right solution as although in theory we might want to say, "BROKENCOBRA and BLOCKED" it seems unlikely in practice.

The added complexity of adding another HDU doesn't seem worth it. However, if we define these enum values use high bits (e.g. BROKENCOBRA = 0x1000 ) we could decide to use e.g. fiberStatus = BLOCKED & BROKENCOBRA if the need arises.