perf: join by row-encoding

[ritchie46]

• Adds join validation for multiple keys.
• Faster multiple key joins
• Negative code count

closes #2377

(note to self, many_bitmap_and_combine and boolean unary without chain).

[codspeed-hq]

CodSpeed Performance Report

Merging #15559 will not alter performance

_{Comparing join (34188ae) with main (b91dedb)}

Summary

✅ 22 untouched benchmarks

[codecov]

Codecov Report

Attention: Patch coverage is 97.65625% with 9 lines in your changes are missing coverage. Please review.

Project coverage is 81.08%. Comparing base (42d3697) to head (34188ae).
Report is 2 commits behind head on main.

Files	Patch %	Lines
crates/polars-ops/src/frame/join/mod.rs	93.15%	5 Missing ⚠️
crates/polars-core/src/chunked_array/float.rs	66.66%	3 Missing ⚠️
crates/polars-ops/src/frame/join/asof/groups.rs	98.64%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main   #15559      +/-   ##
==========================================
- Coverage   81.15%   81.08%   -0.08%     
==========================================
  Files        1367     1367              
  Lines      175313   174858     -455     
  Branches     2530     2530              
==========================================
- Hits       142283   141783     -500     
- Misses      32555    32601      +46     
+ Partials      475      474       -1     

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