[os-tor] - allow to specify outgoing interface

[firefart]

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Is your feature request related to a problem? Please describe. The os-tor plugin currently takes the default routes to the internet which is not always what we want. For example to connect to TOR via a separate VPN client connection already established on opnsense

Describe the solution you'd like

It would be nice to add an option to os-tor to allow to specify the outgoing interface. In my example I have an VPN interface and a WAN interface and want to force tor to use the VPN interface without fiddling with routes.

In torrc there are the OutboundBindAddress* options ( https://man.archlinux.org/man/tor.1.en ) which can be used. This would also mean there needs to be a hook to update the torrc file when a dynamic IP on a selected interface changes (as the option only allows ips, not interface names)

Describe alternatives you've considered

Additional context