Shed: Add a util to find miner based on peerid

[arajasek]

For @dkkapur

Usage: lotus-shed miner-peerid <peerId> <stateRoot>

[codecov]

Codecov Report

Merging #7544 (9ba7f37) into master (d910098) will decrease coverage by 0.11%.
The diff coverage is 0.00%.

@@            Coverage Diff             @@
##           master    #7544      +/-   ##
==========================================
- Coverage   39.84%   39.73%   -0.12%     
==========================================
  Files         632      633       +1     
  Lines       66955    67004      +49     
==========================================
- Hits        26681    26625      -56     
- Misses      35683    35771      +88     
- Partials     4591     4608      +17     

Impacted Files	Coverage Δ
cmd/lotus-shed/main.go	0.00% <0.00%> (ø)
cmd/lotus-shed/miner-peerid.go	0.00% <0.00%> (ø)
chain/stmgr/call.go	67.87% <0.00%> (-7.28%)	⬇️
chain/exchange/client.go	52.96% <0.00%> (-4.67%)	⬇️
node/hello/hello.go	63.63% <0.00%> (-3.41%)	⬇️
chain/sync.go	64.60% <0.00%> (-2.68%)	⬇️
storage/wdpost_sched.go	75.24% <0.00%> (-1.99%)	⬇️
miner/miner.go	55.29% <0.00%> (-1.66%)	⬇️
itests/kit/blockminer.go	93.65% <0.00%> (-1.59%)	⬇️
chain/gen/gen.go	68.61% <0.00%> (-1.24%)	⬇️
... and 11 more

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update d910098...9ba7f37. Read the comment docs.