Monitor attestations

[potuz]

This PR is the third in the implementation of the validator monitor, it should be reviewed after #9899

This PR implements logging of performance for attestations viewed by our tracked validators. For attestations included in blocks it logs

• Timely Head, Source, Target
• Inclusion Slot
• Balance and Balance Change

In addition to the basic information

• Validator Index
• Attested Slot
• Source, Target and Head block roots.

For unagregated and aggregated attestations processed by the node (after P2P validation but not necessarily included in a block), we log only the basic information above.

In addition, for P2P aggregated attestations, we log the event that one of our tracked validators was the aggregator.

The P2P logging (namely not included in blocks) is only performed if the appropriate Beacon State is currently cached to avoid expensive lookups. This requires addition of the appropriate function in the stategen package.

info for reviewers

• This PR includes the most expensive performance hit of the validator monitor: the state copies to log unaggregated and aggregated attestations coming over the wire. I have tested this on Prater and the beacon stays in sync, but this would require testing on testnet to verify if it is a resource intensive operation or not. In principle we are only requesting states from the cache.
• This PR has a larger diff than the previous two, but as a consolation reward, the next PR will only include the addition of metrics and will be minimal.

[terencechain]

👏 First round of feedbacks. Will look again