mathlib3

34f53b6c - refactor(combinatorics/young_tableau): move young diagram modules (#16954)

refactor(combinatorics/young_tableau): move young diagram modules (#16954) Rename `combinatorics/young_tableaux` to `combinatorics/young` and move `combinatorics/young_diagram.lean` to `combinatorics/young/young_diagram.lean`. This is to group all topics related to Young tableaux together. Future additions will be in this directory.