e35b883 fixed an issue with reaching across logical sides.

HOWEVER, as a consequence of this, we no longer have access to items for all of the immersives (besides crafting). This is obviously extremely bad!

For tracking these, whenever we look at a compatible block client side, we'll initialize like we usually do EXCEPT FOR THE ITEMS!

• Add a check to our readyToRender() function that checks that we have the items
• Remove all item setting by anything that extends AbstractImmersiveInfo
• When looking at a block, ask the server for its items. The server should send them back, after usual anticheating stuff is taken care of. Once we receive them, look across our immersives to figure out which immersive said items match with, and put them there.*
• Since swaps take place entirely server-side, we don't need to worry about changing anything there.

*: For now, I'm okay with the side effect for this that an immersive won't update until looked at. So if another player changes items around, it won't reflect for us until we look at it.