Deprecate client/selector (#1767)

* client/{grpc,rpc}: depricate selector (wip)

* {client,cmd}: remove client/selector

* deprecate client/selector

* router/static: fix lookup

* config/cmd: add support for legacy static selector flag

* config/cmd: add support for legacy dns selector flag

util/http/http_test.go

@@ -8,14 +8,15 @@ import (
 
 	"github.com/micro/go-micro/v2/registry"
 	"github.com/micro/go-micro/v2/registry/memory"
+	"github.com/micro/go-micro/v2/router"
+	regRouter "github.com/micro/go-micro/v2/router/registry"
 )
 
 func TestRoundTripper(t *testing.T) {
 	m := memory.NewRegistry()
+	r := regRouter.NewRouter(router.Registry(m))
 
-	rt := NewRoundTripper(
-		WithRegistry(m),
-	)
+	rt := NewRoundTripper(WithRouter(r))
 
 	http.HandleFunc("/", func(w http.ResponseWriter, r *http.Request) {
 		w.Write([]byte(`hello world`))