[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/proxy_linux_test.go

@@ -0,0 +1,56 @@
+//go:build linux && !android
+
+package wgproxy
+
+import (
+	"context"
+	"os"
+	"testing"
+
+	"github.com/netbirdio/netbird/client/iface/wgproxy/ebpf"
+)
+
+func TestProxyCloseByRemoteConnEBPF(t *testing.T) {
+	if os.Getenv("GITHUB_ACTIONS") != "true" {
+		t.Skip("Skipping test as it requires root privileges")
+	}
+	ctx := context.Background()
+
+	ebpfProxy := ebpf.NewWGEBPFProxy(51831)
+	if err := ebpfProxy.Listen(); err != nil {
+		t.Fatalf("failed to initialize ebpf proxy: %s", err)
+	}
+
+	defer func() {
+		if err := ebpfProxy.Free(); err != nil {
+			t.Errorf("failed to free ebpf proxy: %s", err)
+		}
+	}()
+
+	tests := []struct {
+		name  string
+		proxy Proxy
+	}{
+		{
+			name: "ebpf proxy",
+			proxy: &ebpf.ProxyWrapper{
+				WgeBPFProxy: ebpfProxy,
+			},
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			relayedConn := newMockConn()
+			err := tt.proxy.AddTurnConn(ctx, nil, relayedConn)
+			if err != nil {
+				t.Errorf("error: %v", err)
+			}
+
+			_ = relayedConn.Close()
+			if err := tt.proxy.CloseConn(); err != nil {
+				t.Errorf("error: %v", err)
+			}
+		})
+	}
+}