Fix problems with new Electra structs

[jtraglia]

This PR fixes the issues discovered by testing with the Electra reference structures.

• Add electra.AggregationAndProof structure.
• Add electra.SignedAggregationAndProof structure.
• Add electra.AttesterSlashing structure.
• Add VersionedAttesterSlashing structure.
• Add VersionedIndexedAttestation structure.
• Fix ssz-size for CommitteeBits (it's 8 bytes not 1 bit vector, confusing).
• Fix typo when unmarshaling consolidations.
• In SignedConsolidation, make message a pointer.
• Remove ExitsRoot from ExecutionPayloadHeader.
• Use yaml (not json) struct tag for Consolidations.
• Fix input to MerkleizeWithMixin for ExecutionPayload.

One of the tests is still failing, but I'm pretty sure the ref test is wrong here.

I sent this message to hww:

[jtraglia]

It took me quite a while to find this issue. Why was this auto-generated value used? Have you been manually changing this for previous versions?

[mcdee]

This was addressed in sszgen as per ferranbt/fastssz#127 but not sure if it has made it into a release version yet.

[mcdee]

Extra data of 0x is an empty value. In YAML strings don't have to be quoted, as far as I'm aware. You will find that consensus and execution nodes are a little lax when it comes to formatting, so it's likely that you will have to handle that situation.

[jtraglia]

@mcdee I'm not entirely sure how to fix this 0x issue. I can fix our marshaled output, but the test code will marshal it to a string, which has a different value. It will marshal it to 0 (not 0x) there.

func testYAMLFormat(input []byte) string {
	val := make(map[string]any)
	if err := yaml.UnmarshalWithOptions(input, &val, yaml.UseOrderedMap()); err != nil {
		panic(err)
	}
        ...

For example, the following. The top line is the expected output, the bottom line is the actual output:

Any advice here?

[jtraglia]

Ah I found that you did this for Capella. I'll copy this:

[jtraglia]

Pushed a commit which handles that edge case. Also, Hsiao-Wei has acknowledged the issue. I'm going to make a PR to the consensus-specs to get that fixed. The fix might not make it into the next release though.

• Encode zero-length hex-strings with quotes ethereum/consensus-specs#3754