Remove automatic creation of spectroIds in ICS butler.

The ICS butler is minuscule, cut down, version of the DRP butler, and is used both by consumers of ICS data – to load black dots or PFI configs, say – and by the actors which create raw data files. Those actors often use a SpectroIds object to inspect the environment (DNS info, basically) to figure out what site they are running at, or what camera and or spectrograph module they are running on/for.

The pfs.utils Butler constructor accepts such an object, and if none is passed in creates one. This was sketchy at the best of times, but is very bad now because the SpectroIds class was moved out of pfs_utils and into ics_utils.

So, if no specIds object is passed in to the Butler() constructor, do not create one. But also add a dataId dictionary argument to cover the basic use case, where we are only interested in, say, one camera.