eosio-blocklog should be able to split up an existing monolithic blocks.log

[matthewdarwin]

There is a new feature committed to develop branch just now to split blocks.log in chunks. (#8909, #9184) Thank you!

This only applies to blocks.log going forward.

For an existing blockchain, you might want to go back and split up your existing block log file the same way future block.log chunks will be created, so you have a consistent way of doing things.

eosio-blocklog should support doing this.