feat: http provider signing key addition (#10641)

# Which Problems Are Solved

HTTP Request to HTTP providers for Email or SMS are not signed.

# How the Problems Are Solved

Add a Signing Key to the HTTP Provider resources, which is then used to
generate a header to sign the payload.

# Additional Changes

Additional tests for query side of the SMTP provider.

# Additional Context

Closes #10067

---------

Co-authored-by: Marco A. <marco@zitadel.com>
(cherry picked from commit 8909b9a2a6)

internal/notification/handlers/config_email.go

@@ -49,9 +49,10 @@ func (n *NotificationQueries) GetActiveEmailConfig(ctx context.Context) (*email.
 		return &email.Config{
 			ProviderConfig: provider,
 			WebhookConfig: &webhook.Config{
-				CallURL: config.HTTPConfig.Endpoint,
-				Method:  http.MethodPost,
-				Headers: nil,
+				CallURL:    config.HTTPConfig.Endpoint,
+				Method:     http.MethodPost,
+				Headers:    nil,
+				SigningKey: config.HTTPConfig.SigningKey,
 			},
 		}, nil
 	}

internal/notification/handlers/config_sms.go

@@ -45,9 +45,10 @@ func (n *NotificationQueries) GetActiveSMSConfig(ctx context.Context) (*sms.Conf
 		return &sms.Config{
 			ProviderConfig: provider,
 			WebhookConfig: &webhook.Config{
-				CallURL: config.HTTPConfig.Endpoint,
-				Method:  http.MethodPost,
-				Headers: nil,
+				CallURL:    config.HTTPConfig.Endpoint,
+				Method:     http.MethodPost,
+				Headers:    nil,
+				SigningKey: config.HTTPConfig.SigningKey,
 			},
 		}, nil
 	}