consensus: make Header nonce u64

[tcoratger]

Component

consensus, eips, genesis

Describe the feature you would like

At the moment, the nonce field in Header consensus struct is B64:

alloy/crates/consensus/src/header.rs

Line 77 in e01492a

pub nonce: B64,

To match the definition we expect in reth and other repos:

https://github.com/paradigmxyz/reth/blob/3a255a1cabd1f19399b42c1fe9bdcc130ac61c2e/crates/storage/codecs/src/alloy/header.rs#L30

it would be nice to make it u64, would you agree @mattsse ?

Additional context

No response

[Rjected]

Just noting that to do this correctly, we also need to bring back the Encodable / Decodable implementations from before reth switched to alloy types, otherwise this would break RLP encoding.

[mattsse]

technically this is 8bytes, I think we can keep B64, dont think this type is used that often and we can add a helper that converts this to u64

[varun-doshi]

Do we still need a helper to convert it to u64? If so I can take this

[mattsse]

I think we can leave this as b64, because for mainnet this field is now useless anyway and b64 would be more beneficial in case OP starts embedding encoded values in there