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_test.go

@@ -0,0 +1,49 @@
+package libhelm
+
+import (
+	"testing"
+
+	"github.com/portainer/portainer/pkg/libhelm/libhelmtest"
+	"github.com/stretchr/testify/assert"
+)
+
+func Test_ValidateHelmRepositoryURL(t *testing.T) {
+	libhelmtest.EnsureIntegrationTest(t)
+	is := assert.New(t)
+
+	type testCase struct {
+		name    string
+		url     string
+		invalid bool
+	}
+
+	tests := []testCase{
+		{"blank", "", true},
+		{"slashes", "//", true},
+		{"slash", "/", true},
+		{"invalid scheme", "garbage://a.b.c", true},
+		{"invalid domain", "https://invaliddomain/", true},
+		{"not helm repo", "http://google.com", true},
+		{"not valid repo with trailing slash", "http://google.com/", true},
+		{"not valid repo with trailing slashes", "http://google.com////", true},
+		{"bitnami helm repo", "https://charts.bitnami.com/bitnami/", false},
+		{"gitlap helm repo", "https://charts.gitlab.io/", false},
+		{"portainer helm repo", "https://portainer.github.io/k8s/", false},
+		{"elastic helm repo", "https://helm.elastic.co/", false},
+		{"redirect", "https://charts.jetstack.io/", false},
+	}
+
+	for _, test := range tests {
+		func(tc testCase) {
+			t.Run(tc.name, func(t *testing.T) {
+				t.Parallel()
+				err := ValidateHelmRepositoryURL(tc.url)
+				if tc.invalid {
+					is.Errorf(err, "error expected: %s", tc.url)
+				} else {
+					is.NoError(err, "no error expected: %s", tc.url)
+				}
+			})
+		}(test)
+	}
+}