prop224: Update prop224 HSDir code to understand latest descriptor format
The revamp of prop224 client authorization brought many changes to the HS descriptor format.
We need to update the code we wrote in legacy/trac#17238 (moved) so that it uses the new superencrypted descriptor format as specified by: https://gitweb.torproject.org/torspec.git/commit/?id=890779ffec60f067048c4e4a9895ccdd49d183a5