Update: ItemManager is available on the client
- Like server, ticks in the background and cleans up items
- when creating/loading items can optionally specify whether it's client-side or server-side item (checked in exclusive modes)
- Made EnablePooling a replicated var, it disables clientside effects
We have a bunch of client-side item allocations that we don't correctly clean up - this will help deal with that.
Tests: built all modes in editor