Allow registering event listening methods with illegal param type

[ZZZank]

Some mods (e.g. CompatUtil in RLTweaker) will intentionally call private register method to register their event listener, even when the param type is illegal.

This PR fixed this "issue" by making EventListenerFactory generate Consumer<Event> instead of IEventListener, because the functional method in Consumer is void accept(T t);, whose param type class is Object instead of Event.

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Registering event listener in this way is, in my opinion, really stupid and far from best practice, especially when you can just create a new class with legal param type, and prevent loading non-existent event classes by simply not using such class:

class OptionalEventHandler {
    public static void optionalEvent(SomeOptionalEvent event) {
        // ...
    }
}

if (modLoaded("some_mod_that_provides_optional_event")) {
    MinecraftForge.EVENT_BUS.register(OptionalEventHandler.class);
}

[Ecdcaeb]

may check and log a warning?