This adds a convenient per-peer option to set the routing table that associated routes are added to. This functionality is very useful for isolating interfaces from the kernel's global routing and forcing all traffic of a virtual interface (or a group of processes, via e.g. "ip rule add uidrange 10000-10009 lookup 42") through Wireguard.

Most users will be served well by the default "table" setting ("main").

Do the right thing, and use multiple interfaces for policy routing. For example, WireGuard interfaces do not allow multiple routes for the same CIDR range.

wireguard: add per-peer routing table option