[client] Use static requested GUID when creating Windows interface (#2479)

RequestedGUID is the GUID of the created network adapter, which then influences NLA generation deterministically.

With this change, NetBird should not generate multiple interfaces in every restart on Windows.

iface/tun.go

@@ -7,6 +7,9 @@ import (
 	"github.com/netbirdio/netbird/iface/bind"
 )
 
+// CustomWindowsGUIDString is a custom GUID string for the interface
+var CustomWindowsGUIDString string
+
 type wgTunDevice interface {
 	Create() (wgConfigurer, error)
 	Up() (*bind.UniversalUDPMuxDefault, error)