Vectorized hash grouping by a single text column

[akuzm]

Use the UMASH hashes that have a guaranteed lower bound on collisions as the hash table keys.

[codecov]

Codecov Report

Attention: Patch coverage is 50.25554% with 292 lines in your changes missing coverage. Please review.

Project coverage is 81.90%. Comparing base (59f50f2) to head (16d4908).
Report is 688 commits behind head on main.

Files with missing lines	Patch %	Lines
tsl/src/import/umash.c	45.93%	275 Missing and 11 partials ⚠️
...des/vector_agg/hashing/hash_strategy_single_text.c	88.09%	1 Missing and 4 partials ⚠️
tsl/src/nodes/vector_agg/plan.c	50.00%	0 Missing and 1 partial ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #7586      +/-   ##
==========================================
+ Coverage   80.06%   81.90%   +1.83%     
==========================================
  Files         190      241      +51     
  Lines       37181    44262    +7081     
  Branches     9450    11021    +1571     
==========================================
+ Hits        29770    36251    +6481     
- Misses       2997     3654     +657     
+ Partials     4414     4357      -57     

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