Add HA support to endpoints controller (hashicorp#479)

* Support HA for the endpoints controller

- The controller manager allows for multiple instances of the controller to run using leader election. By configuring leader election, one of the instances of the controller (the leader) will run the reconciler. All instances can serve the webhook though, but only on the instances will inject the containers per request.

This requires additional priveleges from an RBAC perspective that will be a part of a helm commit.

subcommand/inject-connect/command.go

@@ -362,7 +362,8 @@ func (c *Command) Run(args []string) int {
 
 	mgr, err := ctrl.NewManager(ctrl.GetConfigOrDie(), ctrl.Options{
 		Scheme:             scheme,
-		LeaderElection:     false,
+		LeaderElection:     true,
+		LeaderElectionID:   "consul-controller-lock",
 		Host:               listenSplits[0],
 		Port:               port,
 		Logger:             zapLogger,