It'd be nice for QuantumGraph generation to recognize when a component dataset like "deepCoadd.wcs" can be obtained from a previous step that produces the full composite (e.g. "deepCoadd").

We can work around this in individual PipelineTasks for now, so this is not a super high priority.  It's also the only kind of composite dataset support I think we should worry about for the forseeable future; everything else is even lower priority.

(I'm also only making this a DAX ticket because I know that's what happens to middleware tickets that don't have teams; this is not a request that Andy Salnikov be responsible for it).