Fix golint for pkg/probe

This change adds comments to exported things and renames the tcp,
http, and exec probe interfaces to just be Prober within their
namespace.

Issue #68026

pkg/registry/core/componentstatus/validator.go

@@ -45,7 +45,7 @@ type Server struct {
 	EnableHTTPS bool
 	TLSConfig   *tls.Config
 	Validate    ValidatorFn
-	Prober      httpprober.HTTPProber
+	Prober      httpprober.Prober
 	Once        sync.Once
 }