Added balance reporter

[janezpodhostnik]

Added a reporter, that outputs all the FlowVaults ad their locations in a big json.

I use gojq to get data from the json.
examples:
cat balance_report_1628871716.json | gojq '[.Data.[].Balance] | add'
cat balance_report_1628871716.json | gojq '.Data | group_by(.LastComposite) | map({LastComposite: .[0].LastComposite, Balance: map(.Balance) | add }) | sort_by(-.Balance) '

This PR also adds elapsed times of migrations and reporters to the logs. The output will look like this:

9:42PM INF migration 0 is done ledger=complete timeTaken=3.887378355s

[codecov-commenter]

Codecov Report

Merging #1154 (d2b6358) into master (bb17974) will decrease coverage by 0.19%.
The diff coverage is 2.72%.

@@            Coverage Diff             @@
##           master    #1154      +/-   ##
==========================================
- Coverage   56.16%   55.96%   -0.20%     
==========================================
  Files         484      485       +1     
  Lines       29820    29929     +109     
==========================================
+ Hits        16747    16751       +4     
- Misses      10787    10893     +106     
+ Partials     2286     2285       -1     

Flag	Coverage Δ
unittests	55.96% <2.72%> (-0.20%)	⬇️

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
...execution-state-extract/execution_state_extract.go	75.00% <0.00%> (-1.48%)	⬇️
cmd/util/ledger/migrations/balance_reporter.go	0.00% <0.00%> (ø)
ledger/complete/ledger.go	60.86% <50.00%> (-0.67%)	⬇️
...nsensus/approvals/veryfing_assignment_collector.go	60.40% <0.00%> (+1.34%)	⬆️

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[Kay-Zee]

Any chance we can also output how long these reporters take? Then we can decide if we want them always on

[janezpodhostnik]

Any chance we can also output how long these reporters take? Then we can decide if we want them always on

Done. I edited the description to reflect this.

[janezpodhostnik]

bors merge

[bors]

Build succeeded:

• Integration Tests (1.15)
• Integration Tests (1.16)
• Lint
• Unit Tests (1.15)
• Unit Tests (1.16)