publish block fix for validator interoperability with lighthouse beacon

[g11tech]

Motivation
This is to make the lodestar validator interop with lighthouse beacon

Description
The lodestar validator was throwing errors on the produceBlock api response as documented in isssue: #3370 .

Reason was that the lodestar validator assumes the version information (phase0, altair) availability in response which was not being provided by lighthouse beacon as its not the part of the spec. This PR adds the ability to extract the version from the slot to get the version.

making WithVersion back compatible with pre altair v1/produceBlock call

The publishBlock api is now being properly consumed and the validator is able to produce blocks.

Closes #issue_number
#3370

Steps to test or reproduce

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Codecov Report

Merging #3376 (81d5080) into master (861f6e4) will decrease coverage by 0.00%.
The diff coverage is n/a.

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+ Hits         2968     2969       +1     
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[dapplion]

@g11tech It is part of the REST API spec! Can you check with Lighthouse devs if they are not adding this info? If not, you should raise an issue on their side.

[dapplion]

@g11tech According to their source code Lighthouse is adding the fork version to the response:

                            let fork_name = block.fork_name(&chain.spec).ok();
                            fork_versioned_response(endpoint_version, fork_name, block)
                                .map(|res| warp::reply::json(&res).into_response())

https://github.com/sigp/lighthouse/blob/fff01b24ddedcd54486e374460855ca20d3dd232/beacon_node/http_api/src/lib.rs?_pjax=%23js-repo-pjax-container%2C%20div%5Bitemtype%3D%22http%3A%2F%2Fschema.org%2FSoftwareSourceCode%22%5D%20main%2C%20%5Bdata-pjax-container%5D#L1019

[g11tech]

@g11tech According to their source code Lighthouse is adding the fork version to the response:

                            let fork_name = block.fork_name(&chain.spec).ok();
                            fork_versioned_response(endpoint_version, fork_name, block)
                                .map(|res| warp::reply::json(&res).into_response())

https://github.com/sigp/lighthouse/blob/fff01b24ddedcd54486e374460855ca20d3dd232/beacon_node/http_api/src/lib.rs?_pjax=%23js-repo-pjax-container%2C%20div%5Bitemtype%3D%22http%3A%2F%2Fschema.org%2FSoftwareSourceCode%22%5D%20main%2C%20%5Bdata-pjax-container%5D#L1019

@dapplion actually on the testnet, when slots start from the genesis, till altair fork epoch, v1/produceBlock is being called instead of v2/productBlock by our validator:
https://github.com/ChainSafe/lodestar/blob/master/packages/validator/src/services/block.ts#L76:L80
and v1 doesn't have the version type.
a very simple approach would be that in WithVersion, getType(version) can be replaced by getType(version||'phase0')

[dapplion]

Oh the root of the problem is that our API is not following the spec. The route produceBlock does not include version. https://github.com/ethereum/beacon-APIs/blob/295ce41a45e297aa21bea5d1695b3060066320e0/apis/validator/block.yaml?_pjax=%23js-repo-pjax-container%2C%20div%5Bitemtype%3D%22http%3A%2F%2Fschema.org%2FSoftwareSourceCode%22%5D%20main%2C%20%5Bdata-pjax-container%5D#L39

I proposed this solution, please take a look and adopt it in your PR if you agree master...linterop

[g11tech]

Oh the root of the problem is that our API is not following the spec. The route produceBlock does not include version. https://github.com/ethereum/beacon-APIs/blob/295ce41a45e297aa21bea5d1695b3060066320e0/apis/validator/block.yaml?_pjax=%23js-repo-pjax-container%2C%20div%5Bitemtype%3D%22http%3A%2F%2Fschema.org%2FSoftwareSourceCode%22%5D%20main%2C%20%5Bdata-pjax-container%5D#L39

I proposed this solution, please take a look and adopt it in your PR if you agree master...linterop

yes, separate serialization for produceBlock makes sense. will incorporate the suggestion and bring it to a working stage! 👍

[g11tech]

@dapplion now the validator is nicely publishing blocks on the lighthouse beacon!

[dapplion]

🚀🚀🙏🙏🎉🎉