feat: Async parquet: Decode parquet on a blocking thread pool

[ritchie46]

No description provided.

[codecov]

Codecov Report

Attention: Patch coverage is 98.43750% with 1 lines in your changes are missing coverage. Please review.

Project coverage is 81.03%. Comparing base (f08914b) to head (d21b256).
Report is 4 commits behind head on main.

Files	Patch %	Lines
crates/polars-io/src/parquet/read_impl.rs	98.43%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main   #15083      +/-   ##
==========================================
- Coverage   81.04%   81.03%   -0.01%     
==========================================
  Files        1338     1338              
  Lines      173771   173828      +57     
  Branches     2456     2456              
==========================================
+ Hits       140832   140868      +36     
- Misses      32471    32493      +22     
+ Partials      468      467       -1     

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