Add better compression support to CLI

[mdekstrand]

This improves the compression support for the CLI, preferring the zstandard module to the zstd command.

[codecov]

Codecov Report

Attention: Patch coverage is 16.66667% with 5 lines in your changes missing coverage. Please review.

Project coverage is 90.39%. Comparing base (52e9054) to head (41865bf).
Report is 4 commits behind head on main.

Files with missing lines	Patch %	Lines
src/lenskit/cli/__init__.py	0.00%	3 Missing ⚠️
src/lenskit/cli/recommend.py	0.00%	1 Missing ⚠️
src/lenskit/cli/train.py	50.00%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #712      +/-   ##
==========================================
- Coverage   90.42%   90.39%   -0.03%     
==========================================
  Files         137      137              
  Lines        9556     9560       +4     
==========================================
+ Hits         8641     8642       +1     
- Misses        915      918       +3     

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