fix(cmd/provider/main.go): External Secrets Store initialization

Currently, even when command-line flag `--enable-external-secret-stores` is passed to the generated provider, the feature is not enabled.

Apparently, `o.Features.Enable(features.EnableAlphaExternalSecretStores)` was missing from the generated code.

I also copied how `o.ESSOptions` are initialized from [one of AWS providers][1], otherwise the program would crash.

[1]: https://github.com/crossplane-contrib/provider-upjet-aws/blob/main/cmd/provider/acm/zz_main.go

cmd/provider/main.go

@@ -11,6 +11,7 @@ import (
 	"time"
 
 	xpv1 "github.com/crossplane/crossplane-runtime/apis/common/v1"
+	"github.com/crossplane/crossplane-runtime/pkg/certificates"
 	xpcontroller "github.com/crossplane/crossplane-runtime/pkg/controller"
 	"github.com/crossplane/crossplane-runtime/pkg/feature"
 	"github.com/crossplane/crossplane-runtime/pkg/logging"
@@ -50,6 +51,8 @@ func main() {
 		namespace                  = app.Flag("namespace", "Namespace used to set as default scope in default secret store config.").Default("crossplane-system").Envar("POD_NAMESPACE").String()
 		enableExternalSecretStores = app.Flag("enable-external-secret-stores", "Enable support for ExternalSecretStores.").Default("false").Envar("ENABLE_EXTERNAL_SECRET_STORES").Bool()
 		enableManagementPolicies   = app.Flag("enable-management-policies", "Enable support for Management Policies.").Default("true").Envar("ENABLE_MANAGEMENT_POLICIES").Bool()
+
+		essTLSCertsPath = app.Flag("ess-tls-cert-dir", "Path of ESS TLS certificates.").Envar("ESS_TLS_CERTS_DIR").String()
 	)
 
 	kingpin.MustParse(app.Parse(os.Args[1:]))
@@ -96,9 +99,19 @@ func main() {
 	}
 
 	if *enableExternalSecretStores {
+		o.Features.Enable(features.EnableAlphaExternalSecretStores)
 		o.SecretStoreConfigGVK = &v1alpha1.StoreConfigGroupVersionKind
 		log.Info("Alpha feature enabled", "flag", features.EnableAlphaExternalSecretStores)
 
+		o.ESSOptions = &tjcontroller.ESSOptions{}
+		if *essTLSCertsPath != "" {
+			log.Info("ESS TLS certificates path is set. Loading mTLS configuration.")
+			tCfg, err := certificates.LoadMTLSConfig(filepath.Join(*essTLSCertsPath, "ca.crt"), filepath.Join(*essTLSCertsPath, "tls.crt"), filepath.Join(*essTLSCertsPath, "tls.key"), false)
+			kingpin.FatalIfError(err, "Cannot load ESS TLS config.")
+
+			o.ESSOptions.TLSConfig = tCfg
+		}
+
 		// Ensure default store config exists.
 		kingpin.FatalIfError(resource.Ignore(kerrors.IsAlreadyExists, mgr.GetClient().Create(context.Background(), &v1alpha1.StoreConfig{
 			ObjectMeta: metav1.ObjectMeta{