OpenVPN Redirect Gateway Option Only Works for IPv4
The "Redirect Gateway" checkbox on the OpenVPN server settings page appears to only push the "redirect-gateway def1" option which only affects IPv4. The way the wording is right now, it would lead one to believe it applies to both IPv4 and IPv6.
The checkbox description should be clarified to indicate it only affects IPv4, and another check box should be added for IPv6 that pushes the "redirect-gateway ipv6" option. This way users can select IPv4 and IPv6 redirection individually.
Add a separate checkbox for OpenVPN servers to redirect an IPv6 gateway now that OpenVPN has a native flag for it. Implements #8082
While here, since local network boxes are hidden when redirect gateway is enabled, do not use the values in those boxes when crafting the configuration. That way the GUI configuration is consistent with the backend.