merge key_state->authenticated and key_state->auth_deferred

merge key_state->authenticated and key_state->auth_deferred

Both are tightly coupled often both are checked at the same time.
Merging them into one state makes the code simpler and also brings
us closer in the direction of a state machine

Signed-off-by: Arne Schwabe <arne@rfc2549.org>
Acked-by: Gert Doering <gert@greenie.muc.de>
Message-Id: <20200706163516.11390-2-arne@rfc2549.org>
URL: https://www.mail-archive.com/openvpn-devel@lists.sourceforge.net/msg20216.html
Signed-off-by: Gert Doering <gert@greenie.muc.de>