feat: add bytes transferred per event

[rvagg]

Ref: filecoin-project/lassie#345

Needs this done on the current DB to bring it up to the schema in here:

ALTER TABLE retrieval_attempts ADD COLUMN bytes_transferred bigint;

As is, with filecoin-project/lassie#345 deployed, this would add an attempt per peer that's involved in a bitswap retrieval, it'll also tag those that are Filecoin SPs in the prometheus metrics. I don't think we currently have insight into how many peers are involved in a retrieval, on average, so I'm not sure how much extra chatter this is going to add to the database.

It won't do anything with the number of bytes transferred per provider other than slot that into the database. We may need to reflect further on the dashboard regarding how/if we want to include that somehow (e.g. some kind of ranking per bytes transferred? maybe a Filecoin SP was involved in a bitswap retrieval but contributed a single block to a 100 block retrieval, do we care?).

[codecov-commenter]

Codecov Report

Merging #71 (eac313e) into main (97897ce) will increase coverage by 0.10%.
The diff coverage is 61.53%.

Additional details and impacted files

@@            Coverage Diff             @@
##             main      #71      +/-   ##
==========================================
+ Coverage   23.27%   23.38%   +0.10%     
==========================================
  Files          10       10              
  Lines        1276     1283       +7     
==========================================
+ Hits          297      300       +3     
- Misses        953      957       +4     
  Partials       26       26              

Files Changed	Coverage Δ
eventrecorder/event.go	59.22% <ø> (ø)
metrics/events.go	0.00% <0.00%> (ø)
eventrecorder/recorder.go	46.99% <100.00%> (+0.56%)	⬆️

[rvagg]

changes made on current db instance