Add progress bar to item-item k-NN training

[mdekstrand]

This adds progress reporting support to the item-item k-NN model building.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 92.25%. Comparing base (f8661c3) to head (4325b4c).
Report is 1 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #391      +/-   ##
==========================================
+ Coverage   92.18%   92.25%   +0.06%     
==========================================
  Files          40       41       +1     
  Lines        3137     3162      +25     
==========================================
+ Hits         2892     2917      +25     
  Misses        245      245              

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