peerproxy: Refactor into separate files and add exclusion filter

Kubernetes-commit: d6907457723a8f9a6eb5a9789424c34286d99528

Author: richabanker

discovery/discovery_client.go

@@ -59,7 +59,6 @@ const (
 	// defaultBurst is the default burst to be used with the discovery client's token bucket rate limiter
 	defaultBurst = 300
 
-	AcceptV1 = runtime.ContentTypeJSON
 	AcceptV1 = runtime.ContentTypeJSON
 	// Aggregated discovery content-type (v2beta1). NOTE: content-type parameters
 	// MUST be ordered (g, v, as) for server in "Accept" header (BUT we are resilient