[data] feat: add MultiSourceDataset for weighted sampling#522

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hjshi84 wants to merge 10 commits intomainfrom

junhao/feature-multisource-dataset

Commits on Feb 28, 2026

Commits on Mar 19, 2026

add control of threads
LiuzcEECS
committed

Commits on Mar 23, 2026

fix multisource
LiuzcEECS
committed