[client] Eliminate UDP proxy in user-space mode (#2712)

In the case of user space WireGuard mode, use in-memory proxy between the TURN/Relay connection and the WireGuard Bind. We keep the UDP proxy and eBPF proxy for kernel mode.

The key change is the new wgproxy/bind and the iface/bind/ice_bind changes. Everything else is just to fulfill the dependencies.

client/iface/wgproxy/factory_usp.go

@@ -0,0 +1,27 @@
+package wgproxy
+
+import (
+	"github.com/netbirdio/netbird/client/iface/bind"
+	proxyBind "github.com/netbirdio/netbird/client/iface/wgproxy/bind"
+)
+
+type USPFactory struct {
+	bind *bind.ICEBind
+}
+
+func NewUSPFactory(iceBind *bind.ICEBind) *USPFactory {
+	f := &USPFactory{
+		bind: iceBind,
+	}
+	return f
+}
+
+func (w *USPFactory) GetProxy() Proxy {
+	return &proxyBind.ProxyBind{
+		Bind: w.bind,
+	}
+}
+
+func (w *USPFactory) Free() error {
+	return nil
+}