perf: Batch Plain Parquet UTF-8 verification

[coastalwhite]

$ POLARS_MAX_THREADS=1 poop './plparbench-before 10 plain.parquet auto' './plparbench-after 10 plain.parquet auto'

Benchmark 1 (3 runs): ./plparbench-before 10 plain.parquet auto
  measurement          mean ± σ            min … max           outliers         delta
  wall_time          13.0s  ±  701ms    12.5s  … 13.8s           0 ( 0%)        0%
  peak_rss           1.46GB ±  407KB    1.46GB … 1.46GB          0 ( 0%)        0%
  cpu_cycles         37.9G  ± 84.2M     37.8G  … 38.0G           0 ( 0%)        0%
  instructions        113G  ± 46.7M      113G  …  113G           0 ( 0%)        0%
  cache_references    426M  ±  397K      425M  …  426M           0 ( 0%)        0%
  cache_misses        111M  ±  777K      110M  …  112M           0 ( 0%)        0%
  branch_misses       634K  ± 53.6K      597K  …  695K           0 ( 0%)        0%
Benchmark 2 (3 runs): ./plparbench-after 10 plain.parquet auto
  measurement          mean ± σ            min … max           outliers         delta
  wall_time          8.55s  ± 36.1ms    8.51s  … 8.58s           0 ( 0%)        ⚡- 34.2% ±  8.7%
  peak_rss           1.46GB ±  179KB    1.46GB … 1.46GB          0 ( 0%)          -  0.0% ±  0.0%
  cpu_cycles         20.6G  ± 3.93M     20.6G  … 20.6G           0 ( 0%)        ⚡- 45.6% ±  0.4%
  instructions       50.0G  ± 11.1M     50.0G  … 50.0G           0 ( 0%)        ⚡- 55.6% ±  0.1%
  cache_references    377M  ±  299K      377M  …  378M           0 ( 0%)        ⚡- 11.4% ±  0.2%
  cache_misses        102M  ± 94.0K      102M  …  102M           0 ( 0%)        ⚡-  8.1% ±  1.1%
  branch_misses       237K  ± 8.80K      229K  …  247K           0 ( 0%)        ⚡

For PLAIN string page decoding, this can significantly improve the performance.

[codecov]

Codecov Report

Attention: Patch coverage is 76.47059% with 4 lines in your changes missing coverage. Please review.

Project coverage is 79.87%. Comparing base (884b2ac) to head (32e7ff7).
Report is 57 commits behind head on main.

Files with missing lines	Patch %	Lines
...lars-parquet/src/arrow/read/deserialize/binview.rs	76.47%	4 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main   #18397      +/-   ##
==========================================
- Coverage   79.87%   79.87%   -0.01%     
==========================================
  Files        1495     1495              
  Lines      200199   200210      +11     
  Branches     2867     2867              
==========================================
+ Hits       159905   159911       +6     
- Misses      39748    39753       +5     
  Partials      546      546              

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