Encryption: Refactor secrets service (#41771)

* Refactor kmsproviders pkg

* Update tests

* Fix linting

Co-authored-by: Joan López de la Franca Beltran <joanjan14@gmail.com>

pkg/services/secrets/secrets.go

@@ -6,6 +6,10 @@ import (
 	"xorm.io/xorm"
 )
 
+const (
+	EnvelopeEncryptionFeatureToggle = "envelopeEncryption"
+)
+
 // Service is an envelope encryption service in charge of encrypting/decrypting secrets.
 // It is a replacement for encryption.Service
 type Service interface {
@@ -24,12 +28,6 @@ type Service interface {
 	GetDecryptedValue(ctx context.Context, sjd map[string][]byte, key, fallback string) string
 }
 
-type ProvidersRegistrar interface {
-	CurrentProviderID() string
-	GetProviders() map[string]Provider
-	RegisterProvider(providerID string, provider Provider)
-}
-
 // Store defines methods to interact with secrets storage
 type Store interface {
 	GetDataKey(ctx context.Context, name string) (*DataKey, error)