Builder Api to construct payload envelope

[bharath-123]

This PR attempts to resolve #575

We introduce a builder prefixed api called ConstructExecutionPayloadEnvelope which takes in the beacon block root of the given slot, execution payload and execution requests. It returns an ExecutionPayloadEnvelope which will have to be signed by the builder and published to the PTC.

[potuz]

Why does this endpoint need the full block? if it's just for verification it should need just the bid, payload and requests, isn't it?

[bharath-123]

Why does this endpoint need the full block? if it's just for verification it should need just the bid, payload and requests, isn't it?

Not sure what you mean by verification here.

This endpoint is for the builders to construct the full ExecutionPayloadEnvelope with the post beacon state root if their bid gets included in the block. I think the beacon block root would be required to construct the correct envelope corresponding to the beacon block.

The builder can sign the envelope externally.

I think passing the beacon block root, payload and execution requests should be good?

[nflaig]

this is no longer required due to ethereum/consensus-specs#5094, builders should be able to easily construct the ExecutionPayloadEnvelope themselves as it is no longer required to do a state transition to compute the state_root

[bharath-123]

Yes I will close this PR for now!