feat: check paths completed for all retrieval types

[rvagg]

Depends on filecoin-project/go-data-transfer#378 for the graphsync part of this. Also includes a little bit of cleanup that makes the diff noisier.

Because traversals don't strictly need to run to any pre-defined completion, we have to check it ourselves - we watch the LastPath in the traversal progress and then check whether it at least fulfils our initial path request.

[codecov-commenter]

Codecov Report

Merging #386 (79b6f80) into rvagg/byte-range-proper (20a1138) will increase coverage by 0.05%.
The diff coverage is 92.66%.

Additional details and impacted files

@@                     Coverage Diff                     @@
##           rvagg/byte-range-proper     #386      +/-   ##
===========================================================
+ Coverage                    76.93%   76.98%   +0.05%     
===========================================================
  Files                           87       87              
  Lines                         6611     6608       -3     
===========================================================
+ Hits                          5086     5087       +1     
+ Misses                        1255     1254       -1     
+ Partials                       270      267       -3     

Files Changed	Coverage Δ
pkg/lassie/lassie.go	73.94% <ø> (ø)
pkg/retriever/retriever.go	89.51% <ø> (ø)
pkg/verifiedcar/verifiedcar.go	84.57% <88.40%> (+3.94%)	⬆️
pkg/internal/testutil/mockclient.go	55.55% <100.00%> (+1.20%)	⬆️
pkg/retriever/bitswapretriever.go	95.65% <100.00%> (+1.68%)	⬆️
pkg/retriever/graphsync/client/client.go	68.01% <100.00%> (ø)
pkg/retriever/graphsyncretriever.go	86.41% <100.00%> (+0.70%)	⬆️
pkg/retriever/httpretriever.go	85.83% <100.00%> (+0.11%)	⬆️
pkg/retriever/parallelpeerretriever.go	93.36% <100.00%> (-0.89%)	⬇️
pkg/storage/duplicateaddercar.go	90.43% <100.00%> (-1.53%)	⬇️

... and 4 files with indirect coverage changes

[rvagg]

Changed to Draft while we consider strategy - maybe via the daemon you don't need/want to signal an error as you technically fulfilled the request and it's up to a upstream party to decide that this is an error. On the CLI we probably want to let the user know.

Also, maybe the error shouldn't be per retriever, perhaps it ought to be validated after the retrieval occurs--in which case maybe the RetrievalStats should include a LastPath from the traversal so we can easily verify it outside of the process?

[rvagg]

some of this will be included in #404, we can opt for checking lassie fetch retrievals and reporting to the user when we have that functionality available, it'll just be a matter of wiring up the pieces