options: Factor out parsing code to separate options_parse.c

options: Factor out parsing code to separate options_parse.c

For easier testability. And because everything that
reduces the length of that file in a sensible manner
is a good idea.

Change-Id: I18e38862df1318740928c6cfa21dc4dcd7d44b89
Signed-off-by: Frank Lichtenheld <frank@lichtenheld.com>
Acked-by: Gert Doering <gert@greenie.muc.de>
Gerrit URL: https://gerrit.openvpn.net/c/openvpn/+/1242
Message-Id: <20251007185110.19267-1-gert@greenie.muc.de>
URL: https://sourceforge.net/p/openvpn/mailman/message/59243506/
Signed-off-by: Gert Doering <gert@greenie.muc.de>