Make a separate config for rabbitevents

[masterjus]

There were few issues when developers try to separate instances for rabbitevents and some other features.

So we need to create a separate config.

1. Create the config stub
2. Make a command like rabbitevents:install or rabbitevents:publish to publsh BroadcastEventsServiceProvider and rabbitevents.php config.
3. The config should make possible to specify which connection to use for rabbitevents.