Add Electra block and state objects from CL spec

[nflaig]

Adds Electra block and state objects from CL spec as per v1.5.0-alpha.5 release and modifications from ethereum/consensus-specs#3875

[rolfyone]

LGTM

[nflaig]

need to apply changes from ethereum/consensus-specs#3875

[ralexstokes]

need to apply changes from ethereum/consensus-specs#3875

following these changes, I think we will want the SignedBlindedBeaconBlock to contain an execution_requests_root instead of the execution_requests data

this would be mirrored in the builder-specs so that we don't need to worry about execution requests leaking any MEV in the builder exchange

[nflaig]

following these changes, I think we will want the SignedBlindedBeaconBlock to contain an execution_requests_root instead of the execution_requests data

makes sense, I applied the changes as per ethereum/builder-specs#101

[ralexstokes]

looks good from a somewhat quick skim, nice work!

[rolfyone]

Merging this as it at least should be close, and smaller PRs will be easier to adjust if any slight tweaks need to be made.