Rename TM_UNTRUSTED to TM_INITIAL, always start session in TM_INITIAL rather than...

Rename TM_UNTRUSTED to TM_INITIAL, always start session in TM_INITIAL rather than TM_ACTIVE or TM_INITIAL

Currently we start new session in TM_ACTIVE or TM_INITIAL depending if
we already have an active session in TM_ACTIVE or not.

With this change, all session will be started in TM_INITIAL both initiated
by a peer but also session by ourselves. This simplifies state transitions
and eliminates the wacky state transition that when we have a failed
reneogitiation (and move TM_ACTIVE to TM_LAME_DUCK) that a new session of
a peer starts in TM_ACTIVE rather than TM_INITIAL

This is a squash of two mailing list patches:

Signed-off-by: Arne Schwabe <arne@rfc2549.org>
Acked-by: Gert Doering <gert@greenie.muc.de>
Message-Id: <20221224194253.3202231-2-arne@rfc2549.org>
URL: https://www.mail-archive.com/openvpn-devel@lists.sourceforge.net/msg25798.html
Signed-off-by: Gert Doering <gert@greenie.muc.de>
Signed-off-by: Arne Schwabe <arne@rfc2549.org>
Acked-by: Gert Doering <gert@greenie.muc.de>
Message-Id: <20221224194253.3202231-3-arne@rfc2549.org>
URL: https://www.mail-archive.com/openvpn-devel@lists.sourceforge.net/msg25795.html
Signed-off-by: Gert Doering <gert@greenie.muc.de>
(cherry picked from commit 7dcde87b7a4323ffb173576d4559e14fcfe4e627)