Introduce "noop" go-micro broker

This introduces a no op broker for go-micro. It is set as the default
broker for all ocis http services. To avoid starting the default http
broker, which opens an unused random http port.

Fixes: https://github.com/owncloud/ocis/issues/3829

services/ocdav/pkg/command/server.go

@@ -6,6 +6,7 @@ import (
 
 	"github.com/cs3org/reva/v2/pkg/micro/ocdav"
 	"github.com/oklog/run"
+	"github.com/owncloud/ocis/v2/ocis-pkg/broker"
 	"github.com/owncloud/ocis/v2/ocis-pkg/config/configlog"
 	"github.com/owncloud/ocis/v2/ocis-pkg/version"
 	"github.com/owncloud/ocis/v2/services/ocdav/pkg/config"
@@ -60,6 +61,7 @@ func Server(cfg *config.Config) *cli.Command {
 					ocdav.VersionString(cfg.Status.VersionString),
 					ocdav.Edition(cfg.Status.Edition),
 					ocdav.MachineAuthAPIKey(cfg.MachineAuthAPIKey),
+					ocdav.Broker(broker.NoOp{}),
 					// ocdav.FavoriteManager() // FIXME needs a proper persistence implementation https://github.com/owncloud/ocis/issues/1228
 					// ocdav.LockSystem(), // will default to the CS3 lock system
 					// ocdav.TLSConfig() // tls config for the http server