[VK] Use Cache controller and Make create/delete pod Concurrently (#373)

* Add k8s.io/client-go/tools/cache package

* Add cache controller

* Add pod creator and terminator

* Pod Synchronizer

* Clean up

* Add back reconcile

* Remove unnecessary space in log

* Incorprate feedbacks

* dep ensure

* Fix the syntax error

* Fix the merge errors

* Minor Refactor

* Set status

* Pass context together with the pod to the pod channel

* Change to use flag to specify the number of pod sync workers

* Remove the unused const

* Use Stable PROD Region WestUS in Test

EastUS2EUAP is not reliable

providers/azure/client/network/main_test.go

@@ -13,7 +13,7 @@ import (
 )
 
 var (
-	location      = "eastus2euap"
+	location      = "westus"
 	resourceGroup = "virtual-kubelet-tests"
 	testAuth      *azure.Authentication
 )