feat(Reth): Explore support for a `ms` timestamp in Emerald

The granularity of block timestamps if right now enforced by Reth and is in seconds.

For chains running on Etherium this is acceptable as the block time is usually multiple seconds. For Emerald, with subsecond blocks we need to see how would supporting this in Emerald look like.

Currently the block timestamp is handled by building a custom version of Reth by accepting blocks with the same timestamp:
#109