Feed List<BlockItemUnparsed> to the ring buffer for streaming blocks

[jsync-swirlds]

As a Block Node Engineer
I want to have a simple List<BlockItemUnparsed> as the object on the ring buffer
So that I have a consistent interface for all services that is entirely service-agnostic.

Technical Considerations:
We discussed object creation rate for all consumers and we determined it's not going to be an issue (around 3-5k/sec in normal usage and no more than 50k/sec under heavy load, which is very small as a percentage of the overall system).
We're now free to transmit block item batches as the type on the mediator ring buffer.

[mattp-swirldslabs]

We discussed object creation rate for all consumers and we determined it's not going to be an issue. We're now free to transmit block item batches as the type on the mediator ring buffer.