Dimitris Athanasiou ee4610c0ca
[7.x][ML] Rename cross validation splitter package (#59529) (#59544)
Renames and moves the cross validation splitter package.

First, the package and classes are renamed from using
"cross validation splitter" to "train test splitter".
Cross validation as a term is overloaded and encompasses
more concepts than what we are trying to do here.

Second, the package used to be under `process` but it does
not make sense to be there, it can be a top level package
under `dataframe`.

Backport of #59529
2020-07-14 18:54:46 +03:00
..