network: prevent adding endpoint routes for addresses on the network

network: prevent adding endpoint routes for addresses on the network

Sometimes a peer might be reachable only over another peer. In that case
PEX could announce an endpoint address already covered by the network routes.
When connecting, asking netifd to route that address breaks access, since
it's only reachable over unet.
Detect this case and skip the netifd host route request.

Signed-off-by: Felix Fietkau <nbd@nbd.name>