Import the UMASH hashing library

[akuzm]

We use it for vectorized hash grouping. For now, add the library separately to figure out the required CMake and CI changes.

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[codecov]

Codecov Report

Attention: Patch coverage is 0% with 529 lines in your changes missing coverage. Please review.

Project coverage is 81.34%. Comparing base (59f50f2) to head (1a4b797).
Report is 713 commits behind head on main.

Files with missing lines	Patch %	Lines
tsl/src/import/umash.c	0.00%	529 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #7616      +/-   ##
==========================================
+ Coverage   80.06%   81.34%   +1.27%     
==========================================
  Files         190      240      +50     
  Lines       37181    44700    +7519     
  Branches     9450    11159    +1709     
==========================================
+ Hits        29770    36360    +6590     
- Misses       2997     3959     +962     
+ Partials     4414     4381      -33     

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