[misc] Move shared components to shared directory (#4286)

Moved the following directories:

```
  - management/client → shared/management/client
  - management/domain → shared/management/domain
  - management/proto → shared/management/proto
  - signal/client → shared/signal/client
  - signal/proto → shared/signal/proto
  - relay/client → shared/relay/client
  - relay/auth → shared/relay/auth
```

and adjusted import paths

shared/relay/client/dialer/ws/ws.go

@@ -0,0 +1,90 @@
+package ws
+
+import (
+	"context"
+	"crypto/tls"
+	"crypto/x509"
+	"errors"
+	"fmt"
+	"net"
+	"net/http"
+	"net/url"
+	"strings"
+
+	"github.com/coder/websocket"
+	log "github.com/sirupsen/logrus"
+
+	"github.com/netbirdio/netbird/relay/server/listener/ws"
+	"github.com/netbirdio/netbird/util/embeddedroots"
+	nbnet "github.com/netbirdio/netbird/util/net"
+)
+
+type Dialer struct {
+}
+
+func (d Dialer) Protocol() string {
+	return "WS"
+}
+
+func (d Dialer) Dial(ctx context.Context, address string) (net.Conn, error) {
+	wsURL, err := prepareURL(address)
+	if err != nil {
+		return nil, err
+	}
+
+	opts := &websocket.DialOptions{
+		HTTPClient: httpClientNbDialer(),
+	}
+
+	parsedURL, err := url.Parse(wsURL)
+	if err != nil {
+		return nil, err
+	}
+	parsedURL.Path = ws.URLPath
+
+	wsConn, resp, err := websocket.Dial(ctx, parsedURL.String(), opts)
+	if err != nil {
+		if errors.Is(err, context.Canceled) {
+			return nil, err
+		}
+		log.Errorf("failed to dial to Relay server '%s': %s", wsURL, err)
+		return nil, err
+	}
+	if resp.Body != nil {
+		_ = resp.Body.Close()
+	}
+
+	conn := NewConn(wsConn, address)
+	return conn, nil
+}
+
+func prepareURL(address string) (string, error) {
+	if !strings.HasPrefix(address, "rel:") && !strings.HasPrefix(address, "rels:") {
+		return "", fmt.Errorf("unsupported scheme: %s", address)
+	}
+
+	return strings.Replace(address, "rel", "ws", 1), nil
+}
+
+func httpClientNbDialer() *http.Client {
+	customDialer := nbnet.NewDialer()
+
+	certPool, err := x509.SystemCertPool()
+	if err != nil || certPool == nil {
+		log.Debugf("System cert pool not available; falling back to embedded cert, error: %v", err)
+		certPool = embeddedroots.Get()
+	}
+
+	customTransport := &http.Transport{
+		DialContext: func(ctx context.Context, network, addr string) (net.Conn, error) {
+			return customDialer.DialContext(ctx, network, addr)
+		},
+		TLSClientConfig: &tls.Config{
+			RootCAs: certPool,
+		},
+	}
+
+	return &http.Client{
+		Transport: customTransport,
+	}
+}