[BUG] EntityEvent.ADD is not invoked on server side on Fabric when server/game starts

[donmor]

EntityEvent.ADD is invoked on both sides on Forge and Fabric if a mob is spawned during the game. However when the level is being initialized, the event is only invoked on client side on Fabric, while on Forge it can be invoked on both server and client.

I think it's not likely to be an intended design, as we expect Architectury to cease differences between mod loaders.