Extend EIP-4844 to include withdrawals

[Inphi]

Updates the EIP-4844 spec extension to include withdrawals. The ExecutionPayloadV2 header is updated to do this. As with #197, this change isn't part of the core spec.

[ralexstokes]

nice work :)

[ralexstokes]

how does this interact w/ the existing ExecutionPayloadV2?

is this extension an alternative fork of the spec?

or should this be a V3 to include the excessDataGas field?

[Inphi]

it's an alternative fork where withdrawals and 4844 are part of the same upgrade.

[Inphi]

so we reuse the existing v2 apis rather than create another one

[ralexstokes]

likely worth adding a note to this effect in this document

[Inphi]

This is already noted here in the document. I can edit it if the wording isn't clear enough.

[Inphi]

I've added more wording to clarify this, including adding V2 API methods to this spec.

[terencechain]

it's an alternative fork where withdrawals and 4844 are part of the same upgrade.

This is different than the consensus spec. The consensus spec is treating them as different forks that are going from bellatrix -> capella -> eip4844. If we implement engine API as it is, then the Capella block processing will fail

[terencechain]

So I think this should be V3

[Inphi]

@ralexstokes any further comments?

[ralexstokes]

I think as long as implementers know what is going on here then this is fine -- we will need to update this in the long run however as we can't have two different v2's

[lightclient]

Generally LGTM. Minor nit: based on the feedback in ACD 150 it seems very unlikely withdrawals and 4844 will be done at the same time, so you may want to consider renaming the structures/methods to V3.

[Inphi]

@lightclient updated the method and type names to V3.
cc: @realbigsean