Add support for int32 in attribute.Any

[MrAlias]

Part of #2162

Also, do not convert to an int just to have Int convert it back to int64.

[codecov]

Codecov Report

Merging #2169 (b3d2274) into main (2b0e139) will increase coverage by 0.0%.
The diff coverage is 100.0%.

@@          Coverage Diff          @@
##            main   #2169   +/-   ##
=====================================
  Coverage   72.3%   72.4%           
=====================================
  Files        176     176           
  Lines      12095   12093    -2     
=====================================
+ Hits        8755    8758    +3     
+ Misses      3102    3098    -4     
+ Partials     238     237    -1     

Impacted Files	Coverage Δ
attribute/kv.go	90.0% <100.0%> (+4.2%)	⬆️
...s/otlp/otlptrace/internal/connection/connection.go	16.4% <0.0%> (+1.5%)	⬆️