MCPServer sets currentPath in watchedDirectories

When starting a chain from a watched directory, ensure a SIP's current path matches the one found in the directory.  This can happen during AIP reingest, where the last know location is not the watched directory it is currently in. Do not change currentPath for DIPs, as they can run in parallel with the originating SIP and overwrite the SIP's information.

Also, related cleanup, mostly removing dead code.

Related to AIP Reingest.
Replace this with the parameter support from #110, too?