mathlib3

2f834701 - chore(probability/independence): create independence folder, split old file into two parts (#18987)

chore(probability/independence): create independence folder, split old file into two parts (#18987) Split `probability/independence` into two files, to put Kolmogorov's zero-one law in its own file. The two new files are placed in an `independence` folder. Also fix a typo in a name in `probability/borel_cantelli`.