Windows: Refactor AFSParseName related name parsing

AFSParseName() is a very long complex function.  Extract the parsing
of RelatedFileObject name parsing to a new function AFSParseRelatedName().
This removed ~160 lines of source code out of AFSParseName().

This changeset is not intended to introduce any functional changes.

Change-Id: If04a1bee0c104461f2d8bc33bca426e9ff71be74
Reviewed-on: http://gerrit.openafs.org/11394
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Jeffrey Altman <jaltman@your-file-system.com>