Add block aggregator service #3086
Description
The GraphQL endpoint for getting blocks is very expensive. It's fine for small amounts of blocks, but gets out of hand with large reequests. It has a lot of overhead for serialization as well as accessing the txs for each transaction.
Instead, we can have a separate service that stores full blocks in the serialize format as they are produced. This way the blocks can be just be sent in the stored format and deserialized client-side.