Allow extracing other integers from peer info and add a unit test for it

Allow extracing other integers from peer info and add a unit test for it

This also ensure that we only really extract the variable we are looking
for. The old code would also consider UV_IV_NCP to be IV_NCP.

Change-Id: Iad94e7a9d0b3be8a8db09e9a20eaac6041470ab6
Signed-off-by: Arne Schwabe <arne@rfc2549.org>
Acked-by: Gert Doering <gert@greenie.muc.de>
Gerrit URL: https://gerrit.openvpn.net/c/openvpn/+/1800
Message-Id: <20260808154933.17540-1-gert@greenie.muc.de>
URL: https://www.mail-archive.com/openvpn-devel@lists.sourceforge.net/msg38241.html
Signed-off-by: Gert Doering <gert@greenie.muc.de>