Consolidate service worker channels and goroutines

[gammazero]

Instead of having every service worker report a failure error and the done status of each goroutine within the service, use a single channel to have all service report on their status and completion.

Fixes #415

[codecov]

Codecov Report

Attention: 42 lines in your changes are missing coverage. Please review.

Comparison is base (ead1a94) 74.10% compared to head (dfae0af) 74.26%.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #417      +/-   ##
==========================================
+ Coverage   74.10%   74.26%   +0.16%     
==========================================
  Files         150      150              
  Lines        9876     9926      +50     
==========================================
+ Hits         7319     7372      +53     
+ Misses       1805     1802       -3     
  Partials      752      752              

Files	Coverage Δ
service/datasetworker/statemonitor.go	82.45% <100.00%> (-1.99%)	⬇️
api/api.go	75.14% <90.00%> (+0.07%)	⬆️
service/contentprovider/bitswap.go	82.35% <83.33%> (-0.51%)	⬇️
service/contentprovider/http.go	67.30% <94.44%> (+2.11%)	⬆️
analytics/analytics.go	69.82% <50.00%> (-0.09%)	⬇️
service/datasetworker/datasetworker.go	79.43% <92.59%> (+0.97%)	⬆️
service/downloadserver/downloadserver.go	73.93% <91.66%> (+1.89%)	⬆️
service/healthcheck/healthcheck.go	78.88% <50.00%> (-0.88%)	⬇️
service/service.go	89.79% <84.37%> (+0.73%)	⬆️
service/dealpusher/dealpusher.go	76.57% <78.26%> (+2.32%)	⬆️
... and 1 more

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