Streaming schematics

### The Problem

With large enough schematics, loading it all into memory at once isn't feasible, as the amount of RAM required outpaces consumer-available levels. Therefore, these schematics can't be pasted at all.

### A Solution

Add extensions to the Sponge schematic format to support streaming. lin-bus was already designed to support streaming NBT, so there's no issues with adding additional constraints on a Sponge schematic to allow for streaming from disk. We can key this off of the additional `Metadata` field.

### Alternatives

Design our own format for streaming. This would result in a loss of interoperability, because with the Sponge format, we can retain compatibility with non-streaming readers as well.

### Anything Else?

_No response_