Revert "Rollback new routing functionality (#1805)" (#1813)

This reverts commit 9f32ccd453.

util/net/net.go

@@ -0,0 +1,17 @@
+package net
+
+import "github.com/google/uuid"
+
+const (
+	// NetbirdFwmark is the fwmark value used by Netbird via wireguard
+	NetbirdFwmark = 0x1BD00
+)
+
+// ConnectionID provides a globally unique identifier for network connections.
+// It's used to track connections throughout their lifecycle so the close hook can correlate with the dial hook.
+type ConnectionID string
+
+// GenerateConnID generates a unique identifier for each connection.
+func GenerateConnID() ConnectionID {
+	return ConnectionID(uuid.NewString())
+}