feat(libhelm) import libhelm into CE pkg directory [EE-4650] (#8138)

* import libhelm and update some paths

* remove file

* update readme

pkg/libhelm/validate_repo.go

@@ -0,0 +1,47 @@
+package libhelm
+
+import (
+	"fmt"
+	"net/http"
+	"net/url"
+	"path"
+	"strings"
+	"time"
+
+	"github.com/pkg/errors"
+)
+
+const invalidChartRepo = "%q is not a valid chart repository or cannot be reached"
+
+func ValidateHelmRepositoryURL(repoUrl string) error {
+	if repoUrl == "" {
+		return errors.New("URL is required")
+	}
+
+	url, err := url.ParseRequestURI(repoUrl)
+	if err != nil {
+		return errors.Wrap(err, fmt.Sprintf("invalid helm chart URL: %s", repoUrl))
+	}
+
+	if !strings.EqualFold(url.Scheme, "http") && !strings.EqualFold(url.Scheme, "https") {
+		return errors.New(fmt.Sprintf("invalid helm chart URL: %s", repoUrl))
+	}
+
+	url.Path = path.Join(url.Path, "index.yaml")
+
+	var client = &http.Client{
+		Timeout: time.Second * 10,
+	}
+	response, err := client.Head(url.String())
+	if err != nil {
+		return errors.Wrapf(err, invalidChartRepo, repoUrl)
+	}
+
+	// Success is indicated with 2xx status codes
+	statusOK := response.StatusCode >= 200 && response.StatusCode < 300
+	if !statusOK {
+		return errors.Errorf(invalidChartRepo, repoUrl)
+	}
+
+	return nil
+}