refactor(rust): Split parquet_source.rs in new-streaming

[nameexhaustion]

Only moves code

[codecov]

Codecov Report

Attention: Patch coverage is 0% with 1333 lines in your changes missing coverage. Please review.

Project coverage is 79.90%. Comparing base (832aa53) to head (3918b95).
Report is 44 commits behind head on main.

Files with missing lines	Patch %	Lines
...tes/polars-stream/src/nodes/parquet_source/init.rs	0.00%	574 Missing ⚠️
...m/src/nodes/parquet_source/row_group_data_fetch.rs	0.00%	233 Missing ⚠️
...tream/src/nodes/parquet_source/row_group_decode.rs	0.00%	199 Missing ⚠️
...ates/polars-stream/src/nodes/parquet_source/mod.rs	0.00%	160 Missing ⚠️
...-stream/src/nodes/parquet_source/metadata_utils.rs	0.00%	113 Missing ⚠️
...eam/src/nodes/parquet_source/mem_prefetch_funcs.rs	0.00%	54 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main   #18649      +/-   ##
==========================================
- Coverage   79.91%   79.90%   -0.01%     
==========================================
  Files        1506     1511       +5     
  Lines      203204   203200       -4     
  Branches     2891     2891              
==========================================
- Hits       162383   162376       -7     
- Misses      40271    40274       +3     
  Partials      550      550              

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.