[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/validator.go

@@ -0,0 +1,28 @@
+package auth
+
+import (
+	"time"
+
+	auth "github.com/netbirdio/netbird/shared/relay/auth/hmac"
+	authv2 "github.com/netbirdio/netbird/shared/relay/auth/hmac/v2"
+)
+
+type TimedHMACValidator struct {
+	authenticatorV2 *authv2.Validator
+	authenticator   *auth.TimedHMACValidator
+}
+
+func NewTimedHMACValidator(secret []byte, duration time.Duration) *TimedHMACValidator {
+	return &TimedHMACValidator{
+		authenticatorV2: authv2.NewValidator(secret),
+		authenticator:   auth.NewTimedHMACValidator(string(secret), duration),
+	}
+}
+
+func (a *TimedHMACValidator) Validate(credentials any) error {
+	return a.authenticatorV2.Validate(credentials)
+}
+
+func (a *TimedHMACValidator) ValidateHelloMsgType(credentials any) error {
+	return a.authenticator.Validate(credentials)
+}