[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_kernel.go

@@ -0,0 +1,47 @@
+//go:build linux && !android
+
+package wgproxy
+
+import (
+	log "github.com/sirupsen/logrus"
+
+	"github.com/netbirdio/netbird/client/iface/wgproxy/ebpf"
+	udpProxy "github.com/netbirdio/netbird/client/iface/wgproxy/udp"
+)
+
+type KernelFactory struct {
+	wgPort int
+
+	ebpfProxy *ebpf.WGEBPFProxy
+}
+
+func NewKernelFactory(wgPort int) *KernelFactory {
+	f := &KernelFactory{
+		wgPort: wgPort,
+	}
+
+	ebpfProxy := ebpf.NewWGEBPFProxy(wgPort)
+	if err := ebpfProxy.Listen(); err != nil {
+		log.Warnf("failed to initialize ebpf proxy, fallback to user space proxy: %s", err)
+		return f
+	}
+	f.ebpfProxy = ebpfProxy
+	return f
+}
+
+func (w *KernelFactory) GetProxy() Proxy {
+	if w.ebpfProxy == nil {
+		return udpProxy.NewWGUDPProxy(w.wgPort)
+	}
+
+	return &ebpf.ProxyWrapper{
+		WgeBPFProxy: w.ebpfProxy,
+	}
+}
+
+func (w *KernelFactory) Free() error {
+	if w.ebpfProxy == nil {
+		return nil
+	}
+	return w.ebpfProxy.Free()
+}