chore(sidecar): refactor payload building module with new alloy-rpc-engine utils

[merklefruit]

Important

This issue is blocked pending new alloy release

Alloy is cooking up very nice utilities to convert Block to payload (as in engine-API execution payload object).
Once they are released on alloy, we should refactor our builder/ module to use them to simplify our flow.

This will allow us to remove a bunch of ethereum_consensus -> alloy compatibility functions finally.

source: https://github.com/alloy-rs/alloy/blob/45547356a593d663746f6f87da60116268452c71/crates/rpc-types-engine/src/payload.rs#L88

[0ex-d]

Let 'em cook! 🧑‍🍳