Implement KMS v2alpha1

- add feature gate
- add encrypted object and run generated_files
- generate protobuf for encrypted object and add unit tests
- move parse endpoint to util and refactor
- refactor interface and remove unused interceptor
- add protobuf generate to update-generated-kms.sh
- add integration tests
- add defaulting for apiVersion in kmsConfiguration
- handle v1/v2 and default in encryption config parsing
- move metrics to own pkg and reuse for v2
- use Marshal and Unmarshal instead of serializer
- add context for all service methods
- check version and keyid for healthz

Signed-off-by: Anish Ramasekar <anish.ramasekar@gmail.com>

test/integration/framework/etcd.go

@@ -198,7 +198,7 @@ func EtcdMain(tests func() int) {
 		// like k8s.io/klog/v2.(*loggingT).flushDaemon()
 		// TODO(#108483): Reduce this number once we address the
 		//   couple remaining issues.
-		if dg := runtime.NumGoroutine() - before; dg <= 10 {
+		if dg := runtime.NumGoroutine() - before; dg <= 15 {
 			return true, nil
 		}
 		// Allow goroutines to schedule and die off.