Add ethereum/engine implementation

[mattsse]

with #8742 we're getting network specific ChainHandlers

the logic should be implemented in a network specific crate: ethereum/engine optimism/engine

We can now start scaffolding the eth setup in ethereum/engine, this will help us getting a feeling for the overall API/DX

TODO

• add ethereum/engine crate
• add entrypoint for creating the ChainOrchestrator and all it's components
• add future/task that drives the orchestrator

This entrypoint should be very similar to:

reth/crates/node/builder/src/launch/mod.rs

Lines 249 to 263 in 5b2cd27

	// Configure the consensus engine
	let (beacon_consensus_engine, beacon_engine_handle) = BeaconConsensusEngine::with_channel(
	client,
	pipeline,
	ctx.blockchain_db().clone(),
	Box::new(ctx.task_executor().clone()),
	Box::new(ctx.components().network().clone()),
	max_block,
	ctx.components().payload_builder().clone(),
	initial_target,
	reth_beacon_consensus::MIN_BLOCKS_FOR_PIPELINE_RUN,
	consensus_engine_tx,
	Box::pin(consensus_engine_stream),
	hooks,
	)?;

I assume we'll end up with something like a helper type that wraps the ChainOrchestrator and some reporting channels (currently beacon_engine_handle.event_listener()) that is either a future itself or has an async fn run(self)