fix: Ensure parquet schema arg is propagated to IR

[nameexhaustion]

Fixes #19081

[nameexhaustion]

Change ParquetOptions::schema to hold our native schema type, this reduces excess copy/conversions as that is the type we receive at input, and also the type we give to the IR. The conversion to arrow schema is now done below in to_alp_impl and stored directly to the FileInfo::reader_schema field

[codecov]

Codecov Report

Attention: Patch coverage is 85.71429% with 1 line in your changes missing coverage. Please review.

Project coverage is 79.76%. Comparing base (35946cf) to head (48bd3a3).
Report is 2 commits behind head on main.

Files with missing lines	Patch %	Lines
...ates/polars-stream/src/nodes/parquet_source/mod.rs	0.00%	1 Missing ⚠️

Additional details and impacted files

@@           Coverage Diff           @@
##             main   #19084   +/-   ##
=======================================
  Coverage   79.76%   79.76%           
=======================================
  Files        1531     1531           
  Lines      208521   208546   +25     
  Branches     2913     2913           
=======================================
+ Hits       166332   166357   +25     
  Misses      41638    41638           
  Partials      551      551           

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