Add load_movielens function to replace old data set classes #442

Job	Run time
Conda Python 3.10 on ubuntu-latest	7m 3s
Conda Python 3.10 on macos-latest	4m 21s
Conda Python 3.10 on windows-latest	12m 2s
Non-JIT test coverage	5m 14s
Conda Python 3.11 on ubuntu-latest	6m 25s
Conda Python 3.11 on macos-latest	4m 38s
Conda Python 3.11 on windows-latest	12m 39s
Vanilla Python 3.10 on ubuntu-latest	6m 5s
Conda Python 3.12 on ubuntu-latest	6m 33s
Vanilla Python 3.10 on macos-latest	3m 5s
Demos, examples, and docs	3m 35s
Conda Python 3.12 on macos-latest	4m 39s
Vanilla Python 3.11 on ubuntu-latest	6m 33s
Conda Python 3.12 on windows-latest	13m 51s
Vanilla Python 3.11 on macos-latest	3m 16s
Evaluation-based tests	12m 14s
Vanilla Python 3.12 on ubuntu-latest	8m 10s
Vanilla Python 3.12 on macos-latest	3m 34s
Minimal dependency tests for FunkSVD	30s
FunkSVD tests on Python 3.10	1m 15s
FunkSVD tests on Python 3.11	39s
HPF bridge tests on Python 3.10	1m 4s
Minimal dependency tests for Implicit	38s
HPF bridge tests on Python 3.11	56s
Implicit bridge tests on Python 3.10	43s
HPF bridge tests on Python 3.12	55s
Implicit bridge tests on Python 3.11	44s
Implicit bridge tests on Python 3.12	1m 54s
Minimal dependency tests	5m 12s
FunkSVD tests on Python 3.12	43s
Test suite results	26s
	2h 19m 36s

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