strongswan: Manually install all routes for non-routed VPNs

strongswan: Manually install all routes for non-routed VPNs

This is a regression from disabling charon.install_routes.

VPNs are routing fine as long as traffic is passing through
the firewall. Traps are not propertly used as long as these
routes are not present and therefore we won't trigger any
tunnels when traffic originates from the firewall.

Fixes: #12045
Signed-off-by: Michael Tremer <michael.tremer@ipfire.org>