Refactor early initialisation and uninitialisation into methods

Refactor early initialisation and uninitialisation into methods

This put the early initialisation and uninitialisation that needs to
happen between option parsing and post processing into small methods.

Cherry-pick of 97056dbf9 as prerequirement for the provider patch

Signed-off-by: Arne Schwabe <arne@rfc2549.org>
Acked-by: Gert Doering <gert@greenie.muc.de>
Message-Id: <20220512121429.2096164-2-arne@rfc2549.org>
URL: https://www.mail-archive.com/openvpn-devel@lists.sourceforge.net/msg24328.html
Signed-off-by: Gert Doering <gert@greenie.muc.de>