Registration callbacks

Internally, most events are created when something required it. For example, you stepped on that specific block.

All events have a "create callback" event, that fires after the event was registered. The ID is the same as the parent event, postfixed with _create_callback. Example: minecraft:block/dirt/placed_create_callback.

This allows pack-makers to disable events, or register new ones, in response to something. Currently, that is the only purpose. They are called as the server itself.

Callback events can not be called by the event command.