REL-2133: Make corrected patrol field an Option[PatrolField]

`GuideProbe` has a `getCorrectedPatrolField` method which sometimes applies transformations to take into account instrument-specific artifacts like the offset for the GMOS IFU.  The problem with the implementation of this method is that it assumes it is always called in a context that contains the associated instrument.  That's not necessarily the case since target components containing guide stars for another instrument's OIWFS can be copied and pasted around across observations in the OT, or guide stars can be added and afterwords the instrument component can be swapped out, etc.

This change makes the corrected patrol field always return an `Option` which is `None` if the context doesn't match what it is expected. That's the one substantive change.  The rest is just matching up the types.
Could the getValue throw an exception?