Translate CW721 events to ERC721 events

[codchen]

Describe your changes and provide context

Similar to #1748 but done for 721 events. Things notable:

• CW721 allows multiple approved spenders to exist for a given token ID, whereas ERC721 assumes there will be at most one. This might cause confusion if applications solely rely on the translated events, since an ERC721 "revoke" event is just an approve event setting spending to 0x0, which would not indicate exactly which one of the multiple CW721 spenders is revoked.
• CW721 has a string-typed token ID, whereas ERC721 has an integer. The translation here would drop any event pertaining to tokens that have a non-integer ID

Testing performed to validate your change

unit tests

[codecov]

Codecov Report

Attention: Patch coverage is 77.19298% with 26 lines in your changes missing coverage. Please review.

Project coverage is 61.14%. Comparing base (b3204f9) to head (b462dcf).

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1750      +/-   ##
==========================================
+ Coverage   60.92%   61.14%   +0.21%     
==========================================
  Files         251      251              
  Lines       21850    21962     +112     
==========================================
+ Hits        13313    13429     +116     
+ Misses       7595     7579      -16     
- Partials      942      954      +12     

Files	Coverage Δ
x/evm/keeper/log.go	38.46% <0.00%> (-4.40%)	⬇️
app/receipt.go	79.59% <80.00%> (+1.48%)	⬆️

... and 4 files with indirect coverage changes