Add predict_pipeline, remove data.bulk module, and clean up batch functions

[mdekstrand]

This does some cleanups, removing the data.bulk module that is no longer needed now that we have item list collections, and adding a predict_pipeline function for use in tests, and adds a score batch function (and moves batch functions around).

[codecov]

Codecov Report

Attention: Patch coverage is 91.42857% with 3 lines in your changes missing coverage. Please review.

Project coverage is 90.70%. Comparing base (4725505) to head (c0d4133).
Report is 6 commits behind head on main.

Files with missing lines	Patch %	Lines
lenskit/lenskit/pipeline/common.py	78.57%	3 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #582      +/-   ##
==========================================
- Coverage   90.71%   90.70%   -0.01%     
==========================================
  Files         108      105       -3     
  Lines        6540     6512      -28     
==========================================
- Hits         5933     5907      -26     
+ Misses        607      605       -2     

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