Describe the problem related to your feature request.

Currently Layer are for entity and chunk, it's would be mildly impractical and casse pied if we start creating different layers for each api were we want layer to be use.
For all componant that impl a layer solution, we attache ourself to one of the two layers, but we need to use filter in our impl which is suboptimale.

What solution would you like?

I personally would see :

In the layer entity side ->

• A LayerMarker componant that store a message queue (like the current one)
• Some [...]LayerData componant
  • EntityLayerData store FxHashMap<ChunkPos, BTreeSet<Entity>>
  • BossBarLayerData store BTreeSet<Entity>
  • ...

On the other componant side ->

• A LayerId componant that store the id of the layer it is on

What alternative(s) have you considered?

We can use the EntityLayer and add the data componant.