Add tracked vpnruntime implementation for CI guard tests

agents/rap-node-agent/internal/vpnruntime/tun_unsupported.go

@@ -0,0 +1,23 @@
+//go:build !linux && !windows
+
+package vpnruntime
+
+import "fmt"
+
+type tunDevice struct{}
+
+func openGatewayTun(name, addressCIDR, routeCIDR string) (*tunDevice, error) {
+	return nil, fmt.Errorf("vpn gateway runtime is currently supported only on linux")
+}
+
+func (d *tunDevice) Read(packet []byte) (int, error) {
+	return 0, fmt.Errorf("vpn gateway runtime is currently supported only on linux")
+}
+
+func (d *tunDevice) Write(packet []byte) (int, error) {
+	return 0, fmt.Errorf("vpn gateway runtime is currently supported only on linux")
+}
+
+func (d *tunDevice) Close() error {
+	return nil
+}