pkg/: FEATURE: support allowed IPs outside a cluster

Users can specify IPs with the annotation "allowed-location-ips".
It makes no difference which node of a location is annotated.
The IP should be routable from the particular location, e.g. a printer in
the same LAN.
This way these IPs become routable from other location.

Signed-off-by: leonnicolas <leonloechner@gmx.de>

Co-authored-by: Lucas Servén Marín <lserven@gmail.com>

pkg/mesh/backend.go

@@ -67,6 +67,7 @@ type Node struct {
 	Subnet              *net.IPNet
 	WireGuardIP         *net.IPNet
 	DiscoveredEndpoints map[string]*wireguard.Endpoint
+	AllowedLocationIPs  []*net.IPNet
 }
 
 // Ready indicates whether or not the node is ready.