Check all IPNS-capable gateways for activity

At least some of them seem non-operational as of right now.

This checker would possibly help to identity IPNS - https://github.com/ipfs/public-gateway-checker/blob/master/src/Ipns.ts & https://github.com/ipfs/public-gateway-checker/blob/4d73419fc1c8d0c7ec0cf9f68f4d938da21b2019/src/constants.ts#L6