discovery: Add profile-based content negotiation

Add support for 'profile=nopeer' in Accept headers to allow clients to opt out of peer-aggregated discovery and request local-only results. Updates discovery client to set appropriate Accept headers based on whether peer-aggregated discovery is desired. Part of KEP-4020: Unknown Version Interoperability Proxy Kubernetes-commit: 6a07342d37a762230209e362d383e1fbfc325b51

Author: richabanker

pkg/endpoints/handlers/negotiation/negotiate.go

@@ -168,6 +168,9 @@ type MediaTypeOptions struct {
 // has set
 Export bool
 
+// profile controls the discovery profile (e.g., "local" for local (non peer-aggregated) discovery)
+Profile string
+
 // unrecognized is a list of all unrecognized keys
 Unrecognized []string
 
@@ -227,6 +230,10 @@ func acceptMediaTypeOptions(params map[string]string, accepts *runtime.Serialize
 case "pretty":
 options.Pretty = v == "1"
 
+// controls the discovery profile (eg local vs peer-aggregated)
+case "profile":
+options.Profile = v
+
 default:
 options.Unrecognized = append(options.Unrecognized, k)
 }