[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/validator.go

@@ -0,0 +1,33 @@
+package hmac
+
+import (
+	"crypto/sha256"
+	"fmt"
+	"time"
+
+	log "github.com/sirupsen/logrus"
+)
+
+type TimedHMACValidator struct {
+	*TimedHMAC
+}
+
+func NewTimedHMACValidator(secret string, duration time.Duration) *TimedHMACValidator {
+	ta := NewTimedHMAC(secret, duration)
+	return &TimedHMACValidator{
+		ta,
+	}
+}
+
+func (a *TimedHMACValidator) Validate(credentials any) error {
+	b, ok := credentials.([]byte)
+	if !ok {
+		return fmt.Errorf("invalid credentials type")
+	}
+	c, err := unmarshalToken(b)
+	if err != nil {
+		log.Debugf("failed to unmarshal token: %s", err)
+		return err
+	}
+	return a.TimedHMAC.Validate(sha256.New, c)
+}