[work in progress] Initial work to do content source refresh with step reporting

Everything is living one file now.  Need to discuss best place to put things.  

I created two steps:

ContentSourceRefreshStep is used to refresh a content source.
ContentCatalogRefresher is used for all sources, so it has ContentSourceRefreshStep child steps.

At this point only the whole catalog refresh works with the step reporting.  The single source reporting will just use the single ContentSourceRefreshStep. 


The *conduit* design pattern has been kind of deprecated by the team.  In addition, this processing is happening in the platform (not a support package).  I suggest that the refresh step(s) use the content.sources package directly instead of the conduit.