Assign owner correctly when there are multiple transfers

[codchen]

Describe your changes and provide context

It is possible to have multiple ERC721 transfers in the same transaction. The previous implementation of owner replacement doesn't account for such scenarios and always use the last pretransfer_owner event to fill in owners for synthetic ERC721 events. This PR fixes it by assigning pretransfer_owner event to the correct transfer event based on order of appearance.

Testing performed to validate your change

unit test that involves multiple transfers in a tx

[codecov]

Codecov Report

Attention: Patch coverage is 75.00000% with 11 lines in your changes missing coverage. Please review.

Project coverage is 61.68%. Comparing base (9432bee) to head (893b496).
Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
app/receipt.go	75.00%	8 Missing and 3 partials ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1956      +/-   ##
==========================================
- Coverage   61.71%   61.68%   -0.03%     
==========================================
  Files         263      263              
  Lines       23425    23447      +22     
==========================================
+ Hits        14456    14463       +7     
- Misses       7963     7979      +16     
+ Partials     1006     1005       -1     

Files with missing lines	Coverage Δ
app/receipt.go	78.68% <75.00%> (-0.47%)	⬇️

... and 2 files with indirect coverage changes

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