Add a mining-heartbeat INFO line at every epoch

[ribasushi]

Make the mining round chattier ( it should be ok: one extra message per epoch )

[benjaminh83]

Extremely valuable for all miners.
Both for debugging, but also much easier to overview the block win process. Normally we have to recognize a block win by the computation of a winningpost. This is much more intuitive and should be the standard of log outputs.
Downside of additional log size is not really a problem with only 1 additional line per 30s.

Output like:
2021-05-04T20:13:06.410+0200 INFO miner miner/miner.go:434 completed mineOne: round:728187 baseHeight:728186 netPower:5646685342788157440 minerPower:258389351792640 isEligible:true isWinner:false

[ribasushi]

Withdrawing from review for a bit, logline needs to be adjusted, too confusing to folks as it is.

[ribasushi]

Slightly modified and expanded, ready for review. Tested on nerpa with and without a win, the log looks like this:

tail -f /srv/efs/lotus_nerpa_miner/lotus-miner.log | grep -E 'mined new block|winAttemptVRF|mineOne'

2021-05-05T17:07:36.172Z        INFO    gen     gen/gen.go:638  completed winAttemptVRF {"VRFb64": "lRaGzH3UH6KAbdckvWwfmgzKN3QzW-yFipNpysSTVWI5EStbYKulDYXlbSGRnmnHGUaQhOgDa1-CeTYnzyvhE-7t64fekuwsRUusxyhuGCy7uaKHrhSx2vSxzeyO17ja", "winCount": 0}
2021-05-05T17:07:36.173Z        INFO    miner   miner/miner.go:382      completed mineOne       {"forRound": 139314, "baseEpoch": 139313, "lookbackEpochs": 900, "networkPowerAtLookback": "16492674416640", "minerPowerAtLookback": "7516192768", "isEligible": true, "isWinner": false}
2021-05-05T17:08:06.492Z        INFO    gen     gen/gen.go:638  completed winAttemptVRF {"VRFb64": "i0UY3q8_N6dNYtlCkyFBswk7NBM_Wh8XtdLx9U3cGPm5iigIl9cpORLZhJdg1FD1FUHLVcGt4AZ7bYWcWifpLMQE13BUIxTQJWxQNputO4kSjikyHttS7DYcn2Jb5YgT", "winCount": 0}
2021-05-05T17:08:06.492Z        INFO    miner   miner/miner.go:382      completed mineOne       {"forRound": 139315, "baseEpoch": 139314, "lookbackEpochs": 900, "networkPowerAtLookback": "16492674416640", "minerPowerAtLookback": "7516192768", "isEligible": true, "isWinner": false}
2021-05-05T17:08:36.377Z        INFO    gen     gen/gen.go:638  completed winAttemptVRF {"VRFb64": "uDYJ0bnhAxGx1V0U2eqLZzXzXuoxmc_L1rIPcnp_Dc6su0yEpfR-_Ri8yUAPyqIEBifntTvzuB863YFvwb3rmSzlinxhH7y8jOqTe6zA4iA8nCFtDq9gvb40oXGGVv6o", "winCount": 1}
2021-05-05T17:08:59.469Z        INFO    miner   miner/miner.go:472      mined new block {"cid": "bafy2bzaceajicralfar3fktgnpiymogbpxhqjnamuwx5mtqe7icczpsdpobjm", "height": 139316, "miner": "t01005", "parents": ["t01001","t01002"], "parentTipset": "{bafy2bzacea5hdeu2yh3fa7qulqws4mgnx76revj6visd4xtyvvar5wcfiqu4i,bafy2bzaceaonfi3oyiagjiqumdbjuoajdryuxg5bddfqnxiklnkoltkbjm2ii}", "took": 23.101306284}
2021-05-05T17:08:59.469Z        INFO    miner   miner/miner.go:382      completed mineOne       {"forRound": 139316, "baseEpoch": 139315, "lookbackEpochs": 900, "networkPowerAtLookback": "16492674416640", "minerPowerAtLookback": "7516192768", "isEligible": true, "isWinner": true}
2021-05-05T17:09:05.910Z        INFO    gen     gen/gen.go:638  completed winAttemptVRF {"VRFb64": "qgdrGhpTRrJNvoR6y36p1r5QtT8P2ArRAhN-kF1Ks8s-ZJoXNTdQuy5u4uDPaTymFA_W-LbwbLMrujRLkXMKnqdwwNU9Rq-KQrWNGeqlF5jng7Qt7_Jfy5etQJ1HnwKm", "winCount": 0}
2021-05-05T17:09:05.911Z        INFO    miner   miner/miner.go:382      completed mineOne       {"forRound": 139317, "baseEpoch": 139316, "lookbackEpochs": 900, "networkPowerAtLookback": "16492674416640", "minerPowerAtLookback": "7516192768", "isEligible": true, "isWinner": false}

[ribasushi]

A bit more verbose vrf line now

2021-05-05T18:40:36.063Z        INFO    gen     gen/gen.go:638  completed winAttemptVRF {"beaconRound": 826966, "beaconDataB64": "lJwA-Ya21Aw5bQ6TNJbIauaGdOnpsfjEfpUd97aryOEUzQmAC_JQ8eFITZpYdhs1Ga-xV3u8sLbK0IiIg04XEVn5IW1yBzzHGrMT-8a686ECa6DjGsLJnnZqS27hoAWR", "electionRandB64": "S5j2kc3G_1ArcQSAPYZcjJZ1arls4RRonwKs7dVe-28", "vrfB64": "mObHmXAHiJHoh-KQ_iTujqDKK-bMCLOx9dQHFyGWEVsoMemArugCqq-42n21X3pjELKFUyF80cTa4n5W0wCqKE4E7poE36233ZX__wwXPIjRhVwNdIK8ww1VOYMNAdaV", "winCount": 0}
2021-05-05T18:40:36.063Z        INFO    miner   miner/miner.go:387      completed mineOne       {"forRound": 139500, "baseEpoch": 139499, "lookbackEpochs": 900, "networkPowerAtLookback": "16492674416640", "minerPowerAtLookback": "7516192768", "isEligible": true, "isWinner": false}