Moved DSpace-specific processing after extraction

refs #5889

Because extraction moved later in the workflow, the existing DSpace
specific chain links were expecting files to be extracted when they
weren't.  Consequently, the fileGrpUse wasn't set, so the USE metadata
in the METS file was not being set either.

Moved DSpace specific processing to after extraction (and made it
possible for other transfer types to have specialized processing here
as well).  Merged Identify DSpace License Files and Identify DSpace
Text Files, since they had only different 2 lines, and cleaned up.