dco-win: support for epoch data channel

dco-win: support for epoch data channel

Starting from 2.8.0, dco-win driver supports epoch data channel.

This commit adds missing userspace part to query DCO drivers for epoch
data format support (always "false" for now for Linux and FreeBSD, true
if Win-DCO driver is 2.8 or later), and pass "CRYPTO_OPTIONS_EPOCH"
flag via a new OVPN_IOCTL_NEW_KEY_V2 ioctl() to windows driver to turn
it on, if negotiated.

Change-Id: Ib5ed5969dcd405a47e34ed8479b7ffaaa5c43080
Signed-off-by: Lev Stipakov <lev@openvpn.net>
Acked-by: Arne Schwabe <arne-openvpn@rfc2549.org>
Gerrit URL: https://gerrit.openvpn.net/c/openvpn/+/1219
Message-Id: <20251008123757.18670-1-gert@greenie.muc.de>
URL: https://sourceforge.net/p/openvpn/mailman/message/59243920/
Signed-off-by: Gert Doering <gert@greenie.muc.de>