Implements https://github.com/cerc-io/go-ethereum/issues/319
With this we can perform a single pass to process updates.
Also
* refactor code structure around single-pass iteration
* refactor builder metrics to match new set of functions
* fix unit tests by running sequentially
* update ipld-eth-db in compose
* factor out fixture data into external module
* some CI updates
Reviewed-on: #11
