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/istio.io/api/policy/v1beta1/http_response_json.gen.go

@@ -0,0 +1,33 @@
+// Code generated by protoc-gen-gogo. DO NOT EDIT.
+// source: policy/v1beta1/http_response.proto
+
+package v1beta1
+
+import (
+	bytes "bytes"
+	fmt "fmt"
+	github_com_gogo_protobuf_jsonpb "github.com/gogo/protobuf/jsonpb"
+	proto "github.com/gogo/protobuf/proto"
+	math "math"
+)
+
+// Reference imports to suppress errors if they are not otherwise used.
+var _ = proto.Marshal
+var _ = fmt.Errorf
+var _ = math.Inf
+
+// MarshalJSON is a custom marshaler for DirectHttpResponse
+func (this *DirectHttpResponse) MarshalJSON() ([]byte, error) {
+	str, err := HttpResponseMarshaler.MarshalToString(this)
+	return []byte(str), err
+}
+
+// UnmarshalJSON is a custom unmarshaler for DirectHttpResponse
+func (this *DirectHttpResponse) UnmarshalJSON(b []byte) error {
+	return HttpResponseUnmarshaler.Unmarshal(bytes.NewReader(b), this)
+}
+
+var (
+	HttpResponseMarshaler   = &github_com_gogo_protobuf_jsonpb.Marshaler{}
+	HttpResponseUnmarshaler = &github_com_gogo_protobuf_jsonpb.Unmarshaler{}
+)