fix(python): Add missing "truncate_ragged_lines" parameter to read_csv_batched

[alexander-beedie]

• Support for "truncate_ragged_lines" existed, but it wasn't exposed - fixed.
• As a minor drive-by, added a bit more detail to the "decimal_comma" docstring.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 81.25%. Comparing base (b6441d0) to head (6d40cdb).

Additional details and impacted files

@@            Coverage Diff             @@
##             main   #15944      +/-   ##
==========================================
- Coverage   81.25%   81.25%   -0.01%     
==========================================
  Files        1381     1381              
  Lines      176636   176636              
  Branches     3034     3034              
==========================================
- Hits       143532   143526       -6     
- Misses      32622    32626       +4     
- Partials      482      484       +2     

Flag	Coverage Δ
python	74.69% <ø> (-0.01%)	⬇️
rust	78.38% <ø> (-0.01%)	⬇️

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