feat(net): Rollup client P2P domains

[merklefruit]

Note

based on paradigmxyz/reth-exex-examples#15

We will need a p2p service responsible for discovery of other rollup nodes, peering and handling gossipsub events.
Ideally this component should be usable in both the CL node implementation and the Kona-ExEx, as a component to apply new unsafe blocks to the current chain. When in sequencer-mode, it should also be possible to broadcast to the new blocks topic.

Here is an overview of the complete functionality according to the specs:

• Discovery with DiscV5 and the Optimism-specific ENR encoding
• Gossipsub domain with topics to subscribe to and publish unsafe blocks
• Optimism-specific payload encoding & decoding from gossip topics
• Request-response domain with an optional payload_by_number endpoint to support gaps in unsafe head sync

This component should live under crates/net.