Ranged block reads

[mattp-swirldslabs]

As part of the Streaming Historic Blocks story
I want to be able to read a range of blocks from the persistence service
So that I can more efficiently fetch a sequence of blocks

Tech notes

• This is needed by: EPIC: Consumer to stream blocks from a specified block number #368
• If the range requested does not exactly map to the available blocks, it would be nice for the List<Block> read(long startBlockNumber, long endBlockNumber) method to respond with what it can find in the range. So, requested: 1 - 10 blocks but available: 1 - 5 then return a list with 1 - 5
• If no blocks are found in the range, return an empty list rather than null or an error.