Add large attachment syncing

[DennisOchulor]

This PR mainly does two things:

1. Change ClientboundAttachmentSyncPayload to handle only one attachment. Initial syncs are sent in a bundle packet.
2. Allow mods to register synced attachments with a configurable max sync size that can go above the vanilla S2C limit.

Supersedes #4996

[modmuss50]

Looks good to me, just noticed one little thing.

[modmuss50]

Also a merge conflict, should be an easy fix.

[DennisOchulor]

Quoting @jacobsjo's comment here

It might solve some issues, but not the one I've reported in this issue. This issue is about the very harsh handling of oversized packets, which can happen no matter what the limit is set to.

Instead of crashing the server, the only other thing that could be done is to just log a warning since at certain points where AttachmentChange is created, it is not known which clients it should be synced too yet.

Though personally I think crashing the server is fine, especially since the default limit is now 1 MiB. If modders are unknowingly syncing more than that, they should probably be forced to make a proper decision about going above it.