eventbus: add generic support for event name (#18805)

vlib/v/tests/fn_voidptr_param_call_with_nonpointer_rvalue_test.v

@@ -5,7 +5,7 @@ struct MyMessage {
 }
 
 fn test_fn_call_with_nonpointer_rvalue() {
-	eb := eventbus.new()
+	eb := eventbus.new[string]()
 	mut subscriber := eb.subscriber
 
 	subscriber.subscribe('my_publish', subscriber_method)
@@ -18,6 +18,6 @@ fn subscriber_method(receiver voidptr, ev &MyMessage, sender voidptr) {
 	println(ev)
 }
 
-fn do_something(eb &eventbus.EventBus) {
+fn do_something[T](eb &eventbus.EventBus[T]) {
 	eb.publish('my_publish', eb, MyMessage{ msg: 'this is my message' })
 }