Enable multi node attestation consensus for the VC

[eserilev]

Allow for the VC to query all BN's at the beginning of each epoch and only enable attestation for that epoch if source and target checkpoint matches for a threshold of BN's

TODO

• make sure we are only comparing relevant fields in attestation data
• As an optimization only check attestation data for the first slot in an epoch
• Ensure we only fetch attestation data for the BN whose attestation data matches consensus
• Allow for consensus threshold to be set via CLI flag
• Write tests
• Test w/ single and multi bn setups w/ multiple consensus thresholds

[eserilev]

@yorickdowne based on our convo in Buenos Aires, I thought you might find this draft PR interesting

[galaxy-tbehrens]

Yes, I find it very interesting! Thank you! (This is the corpo account. I'm forwarding this to the Galaxy team as a potential option)