Add new AuthzSendForbiddenOnFailure directive to allow sending '403 FORBIDDEN'

instead of '401 UNAUTHORIZED' if authorization fails for an authenticated user

PR: 40721


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@1050677 13f79535-47bb-0310-9956-ffa450edef68