For simplicity, we use with_pow() + pseudo peer that connects to reth itself, so that it can support 1. StateFetcher via NetworkState 2. Block announcement (which requires with_pow()).
For block announcement, another way was using ImportService like before, or calling engine_api. But for simplicitiy, for now we just publish from pseudo peer like pre-PoS, hence with_pow().
Like OpTransactionSigned, introduce a new tx type. Not a trivial change but might be beneficial for potential system tx changes e.g., in case it's separated into another tx type
