Registry router fixes (#1961)

* only cache routes if told to do so

* Use roundrobin selector and retry in proxy

* Update lookup to require service

* Fix compile

* Fix compile

* Update

* Update

* rename query to lookup

* Update router.go

* Update

resolver/registry/registry.go

@@ -2,9 +2,9 @@
 package registry
 
 import (
-	"github.com/micro/go-micro/v3/resolver"
 	"github.com/micro/go-micro/v3/registry"
 	"github.com/micro/go-micro/v3/registry/mdns"
+	"github.com/micro/go-micro/v3/resolver"
 )
 
 // Resolver is a registry network resolver