[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/auth/hmac/store.go

@@ -0,0 +1,44 @@
+package hmac
+
+import (
+	"encoding/base64"
+	"fmt"
+	"sync"
+
+	v2 "github.com/netbirdio/netbird/shared/relay/auth/hmac/v2"
+)
+
+// TokenStore is a simple in-memory store for token
+// With this can update the token in thread safe way
+type TokenStore struct {
+	mu    sync.Mutex
+	token []byte
+}
+
+func (a *TokenStore) UpdateToken(token *Token) error {
+	a.mu.Lock()
+	defer a.mu.Unlock()
+	if token == nil {
+		return nil
+	}
+
+	sig, err := base64.StdEncoding.DecodeString(token.Signature)
+	if err != nil {
+		return fmt.Errorf("decode signature: %w", err)
+	}
+
+	tok := v2.Token{
+		AuthAlgo:  v2.AuthAlgoHMACSHA256,
+		Signature: sig,
+		Payload:   []byte(token.Payload),
+	}
+
+	a.token = tok.Marshal()
+	return nil
+}
+
+func (a *TokenStore) TokenBinary() []byte {
+	a.mu.Lock()
+	defer a.mu.Unlock()
+	return a.token
+}