Enable independent CL/EL sync (EIP-8237)

[potuz]

This PR implements EIP 8237 that allows for independent sync on the EL and the CL so that the CL does not download payloads on range sync.

[ahshum]

Does beacon_block gossip need to be updated? It seems that the first block on gossip could be affected?
https://github.com/ethereum/consensus-specs/blob/v1.7.0-alpha.5/specs/gloas/p2p-interface.md?plain=1#L283-L289

[potuz]

Does beacon_block gossip need to be updated? It seems that the first block on gossip could be affected? https://github.com/ethereum/consensus-specs/blob/v1.7.0-alpha.5/specs/gloas/p2p-interface.md?plain=1#L283-L289

Gossip should not be affected at all, but yes, before syncing the first beacon block by gossip you need to request the payload by root, which is something we do already when we haven't got the payload on gossip.

[arnetheduck]

An alternative to this idea is to specify explicitly how the block hash verifiction check happens, ie exactly what bytes are passed to sha256 in the rlp-encoding of the block header, thus avoiding an explicit requirement on RLP but also avoiding the need for yet another accumulator / hash / computation.

[arnetheduck]

Also noteworthy: https://eips.ethereum.org/EIPS/eip-7807 removes the need for separate block hash algorithms between el and cl, which removes this problem from sync altogether