Windows: Remove HELP from afscreds

Windows: Remove HELP from afscreds

The old .hlp format is no longer supported and the text of the
help files is long out of date.  Remove the HELP buttons from
the dialogs and all references to WM_HELP message processing
from the application.

Change-Id: I4c735993c7a79d46cbbc49440aa6d77b6861ff85
Reviewed-on: http://gerrit.openafs.org/7648
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Jeffrey Altman <jaltman@your-file-system.com>
Tested-by: Jeffrey Altman <jaltman@your-file-system.com>