[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/utils.go

@@ -0,0 +1,48 @@
+package oci
+
+import (
+	"errors"
+	"fmt"
+	"io"
+	"net/http"
+	"strings"
+)
+
+// defaultMaxMetadataBytes specifies the default limit on how many response
+// bytes are allowed in the server's response to the metadata APIs.
+// See also: Repository.MaxMetadataBytes
+var defaultMaxMetadataBytes int64 = 4 * 1024 * 1024 // 4 MiB
+
+// errNoLink is returned by parseLink() when no Link header is present.
+var errNoLink = errors.New("no Link header in response")
+
+// parseLink returns the URL of the response's "Link" header, if present.
+func parseLink(resp *http.Response) (string, error) {
+	link := resp.Header.Get("Link")
+	if link == "" {
+		return "", errNoLink
+	}
+	if link[0] != '<' {
+		return "", fmt.Errorf("invalid next link %q: missing '<'", link)
+	}
+	if i := strings.IndexByte(link, '>'); i == -1 {
+		return "", fmt.Errorf("invalid next link %q: missing '>'", link)
+	} else {
+		link = link[1:i]
+	}
+
+	linkURL, err := resp.Request.URL.Parse(link)
+	if err != nil {
+		return "", err
+	}
+	return linkURL.String(), nil
+}
+
+// limitReader returns a Reader that reads from r but stops with EOF after n
+// bytes. If n is zero, defaultMaxMetadataBytes is used.
+func limitReader(r io.Reader, n int64) io.Reader {
+	if n == 0 {
+		n = defaultMaxMetadataBytes
+	}
+	return io.LimitReader(r, n)
+}