post https://api.zan.top/node/v1/eth/mainnet//eth/v1/validator/beacon_committee_subscriptions
Signal beacon node to prepare for a committee subnet.
After beacon node receives this request,
search using discv5 for peers related to this subnet
and replace current peers with those ones if necessary
If validator is_aggregator, beacon node must:
- announce subnet topic subscription on gossipsub
- aggregate attestations received on that subnet