ux: print absolute time for proving period start in proving cli

[magik6k]

Proposed Changes

Print absolute time for (next) proving period start in lotus-miner proving info.

Example output now:

Current Epoch:           1946257
Proving Period Boundary: 975
Proving Period Start:    1944975 (01 Jul 22 08:07 CEST, 10 hours 41 minutes ago)
Next Period Start:       1947855 (02 Jul 22 08:07 CEST, in 13 hours 19 minutes)

Faults:      0 (0.00%)
Recovering:  0
Deadline Index:       21
Deadline Sectors:     0
Deadline Open:        1946235 (11 minutes ago)
Deadline Close:       1946295 (in 19 minutes)
Deadline Challenge:   1946215 (21 minutes ago)
Deadline FaultCutoff: 1946165 (46 minutes ago)

[codecov]

Codecov Report

Merging #8954 (9bfb370) into master (f46cfb4) will increase coverage by 5.57%.
The diff coverage is 64.28%.

@@            Coverage Diff             @@
##           master    #8954      +/-   ##
==========================================
+ Coverage   35.08%   40.66%   +5.57%     
==========================================
  Files         702      706       +4     
  Lines       78426    78660     +234     
==========================================
+ Hits        27517    31984    +4467     
+ Misses      45921    41208    -4713     
- Partials     4988     5468     +480     

Impacted Files	Coverage Δ
cli/state.go	1.03% <0.00%> (ø)
cli/util.go	70.58% <70.00%> (-0.25%)	⬇️
cmd/lotus-miner/proving.go	25.92% <100.00%> (ø)
storage/pipeline/currentdealinfo.go	73.80% <0.00%> (-2.39%)	⬇️
markets/storageadapter/client.go	40.55% <0.00%> (-1.85%)	⬇️
storage/sealer/sched.go	84.61% <0.00%> (-1.29%)	⬇️
storage/wdpost/wdpost_run.go	70.59% <0.00%> (-0.78%)	⬇️
storage/sealer/sched_worker.go	80.00% <0.00%> (-0.59%)	⬇️
storage/wdpost/wdpost_changehandler.go	98.11% <0.00%> (-0.48%)	⬇️
miner/miner.go	58.36% <0.00%> (ø)
... and 148 more