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/github.com/blang/semver/sort.go

@@ -0,0 +1,28 @@
+package semver
+
+import (
+	"sort"
+)
+
+// Versions represents multiple versions.
+type Versions []Version
+
+// Len returns length of version collection
+func (s Versions) Len() int {
+	return len(s)
+}
+
+// Swap swaps two versions inside the collection by its indices
+func (s Versions) Swap(i, j int) {
+	s[i], s[j] = s[j], s[i]
+}
+
+// Less checks if version at index i is less than version at index j
+func (s Versions) Less(i, j int) bool {
+	return s[i].LT(s[j])
+}
+
+// Sort sorts a slice of versions
+func Sort(versions []Version) {
+	sort.Sort(Versions(versions))
+}