Export Prometheus monitoring endpoints

[michaelfig]

Have the deployment mechanism export metrics for the testnet validators as described in https://medium.com/cypher-core/cosmos-how-to-set-up-your-own-network-monitoring-dashboard-fe49c63a8271

This would add new read-only web services on TCP ports 9100 (for host-level monitoring) and 26660 (for tendermint monitoring). To secure them, the validator firewall should at most enable TCP access to these ports by its owner's Prometheus aggregator (which can itself be behind a reverse proxy secured with HTTPS and basic authentication or client certificates).

Of course, if the owner of the validator does not use our deployment mechanism, the default ag-chain-cosmos configuration does not enable these services or expose those ports.