Better ordering, more logging, and disconnect handler fixes on Windows

Better ordering, more logging, and disconnect handler fixes on Windows

Set up the explicit route to the VPN gateway before configuring *anything else*,
and include default/Internet-facing gateway in the logging output.

Fixed a couple issues in the 'disconnect' handler.  We missed these until
now because the 'disconnect' handler was *never being run on Windows* due to
https://gitlab.com/openconnect/openconnect/-/issues/362, until this was
fixed in https://gitlab.com/openconnect/openconnect/-/merge_requests/323

1. Need to specify 'store=active' when deleting an IPv6 address on disconnect
   (missed this in 3a11fc7c971a28e375cc1fb2defe9d829aed2a4f)
2. Put some logging on the 'disconnect' handler.

Signed-off-by: Daniel Lenski <dlenski@gmail.com>