perf: Add/fix unordered row decode, change unordered format

[orlp]

No description provided.

[codecov]

Codecov Report

Attention: Patch coverage is 25.37313% with 50 lines in your changes missing coverage. Please review.

Project coverage is 80.02%. Comparing base (7472a76) to head (6a389da).
Report is 31 commits behind head on main.

Files with missing lines	Patch %	Lines
crates/polars-row/src/variable.rs	20.63%	50 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main   #19284      +/-   ##
==========================================
- Coverage   80.11%   80.02%   -0.09%     
==========================================
  Files        1526     1528       +2     
  Lines      209338   209846     +508     
  Branches     2418     2419       +1     
==========================================
+ Hits       167707   167926     +219     
- Misses      41081    41369     +288     
- Partials      550      551       +1     

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