feat: Targets now emit record count from the built-in batch file processor

[edgarrmondragon]

Closes #2702

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📚 Documentation preview 📚: https://meltano-sdk--2703.org.readthedocs.build/en/2703/

[codspeed-hq]

CodSpeed Performance Report

Merging #2703 will not alter performance

_{Comparing edgarrmondragon/feat/records-batch-metric (59a8d34) with main (8c7c307)}

Summary

✅ 6 untouched benchmarks

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 90.84%. Comparing base (8c7c307) to head (59a8d34).
Report is 1 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #2703   +/-   ##
=======================================
  Coverage   90.84%   90.84%           
=======================================
  Files          62       62           
  Lines        5143     5145    +2     
  Branches      662      662           
=======================================
+ Hits         4672     4674    +2     
  Misses        330      330           
  Partials      141      141           

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