broker: refactor (#396)

* remove subscribe from server
* remove publish from client
* broker package refactoring

Co-authored-by: vtolstov <vtolstov@users.noreply.github.com>
Reviewed-on: #396
Co-authored-by: Vasiliy Tolstov <v.tolstov@unistack.org>
Co-committed-by: Vasiliy Tolstov <v.tolstov@unistack.org>

service.go

@@ -95,11 +95,6 @@ func RegisterHandler(s server.Server, h interface{}, opts ...server.HandlerOptio
 	return s.Handle(s.NewHandler(h, opts...))
 }
 
-// RegisterSubscriber is syntactic sugar for registering a subscriber
-func RegisterSubscriber(topic string, s server.Server, h interface{}, opts ...server.SubscriberOption) error {
-	return s.Subscribe(s.NewSubscriber(topic, h, opts...))
-}
-
 type service struct {
 	done chan struct{}
 	opts Options