[release-4.1] feat: Adapt to oci-based helmchart repo (#6203)

* add oci client for registry

* add LoadRepoIndexFormOci

* feat: Adapt to oci-based helmchart repo

* Update the golang base image version in the dockerfile

* update oci_test.go

Signed-off-by: lingbo <lingbo@lingbohome.com>

* fix: Update oci_test.go

Signed-off-by: 凌波 <lingbo@lingbohome.com>

* Update go imports

---------

Signed-off-by: lingbo <lingbo@lingbohome.com>
Signed-off-by: 凌波 <lingbo@lingbohome.com>
Co-authored-by: lingbo <lingbo@lingbohome.com>
Co-authored-by: hongming <coder.scala@gmail.com>

pkg/simple/client/oci/url.go

@@ -0,0 +1,22 @@
+package oci
+
+import (
+	"fmt"
+
+	"oras.land/oras-go/pkg/registry"
+)
+
+func buildScheme(plainHTTP bool) string {
+	if plainHTTP {
+		return "http"
+	}
+	return "https"
+}
+
+func buildRegistryBaseURL(plainHTTP bool, ref registry.Reference) string {
+	return fmt.Sprintf("%s://%s/v2/", buildScheme(plainHTTP), ref.Host())
+}
+
+func buildRegistryCatalogURL(plainHTTP bool, ref registry.Reference) string {
+	return fmt.Sprintf("%s://%s/v2/_catalog", buildScheme(plainHTTP), ref.Host())
+}