object FabricManagedEventsFabric implementation of [ManagedListenerProvider].
Fabric's event system ([Event]) does not support individual callback unregistration. To work around this, each managed listener wraps the user callback in a dynamic proxy with an active flag. On reload, all WORLD/SERVER_CACHE-scoped wrappers are deactivated.
Initialized once in [KattonFabric.onInitialize] via [initialize].
