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. <[email protected]>

cmd/start/start.go

@@ -205,6 +205,8 @@ func startZitadel(ctx context.Context, config *Config, masterKey string, server
 		keys.OIDC,
 		keys.SAML,
 		keys.Target,
+		keys.SMS,
+		keys.SMTP,
 		config.InternalAuthZ.RolePermissionMappings,
 		sessionTokenVerifier,
 		func(q *query.Queries) domain.PermissionCheck {