use istio client-go library instead of knative (#1661)

use istio client-go library instead of knative
bump kubernetes dependency version
change code coverage to codecov

vendor/k8s.io/code-generator/pkg/namer/tag-override.go

@@ -0,0 +1,58 @@
+/*
+Copyright 2016 The Kubernetes Authors.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package namer
+
+import (
+	"k8s.io/gengo/namer"
+	"k8s.io/gengo/types"
+)
+
+// TagOverrideNamer is a namer which pulls names from a given tag, if specified,
+// and otherwise falls back to a different namer.
+type TagOverrideNamer struct {
+	tagName  string
+	fallback namer.Namer
+}
+
+// Name returns the tag value if it exists. It no tag was found the fallback namer will be used
+func (n *TagOverrideNamer) Name(t *types.Type) string {
+	if nameOverride := extractTag(n.tagName, append(t.SecondClosestCommentLines, t.CommentLines...)); nameOverride != "" {
+		return nameOverride
+	}
+
+	return n.fallback.Name(t)
+}
+
+// NewTagOverrideNamer creates a namer.Namer which uses the contents of the given tag as
+// the name, or falls back to another Namer if the tag is not present.
+func NewTagOverrideNamer(tagName string, fallback namer.Namer) namer.Namer {
+	return &TagOverrideNamer{
+		tagName:  tagName,
+		fallback: fallback,
+	}
+}
+
+// extractTag gets the comment-tags for the key.  If the tag did not exist, it
+// returns the empty string.
+func extractTag(key string, lines []string) string {
+	val, present := types.ExtractCommentTags("+", lines)[key]
+	if !present || len(val) < 1 {
+		return ""
+	}
+
+	return val[0]
+}