Plot_tree Rotate parameter isn't taken into account

[cmarmo]

Description

The rotate parameter has no effect in sklearn.tree.plot_tree function.

After checking the code the rotate parameter has been inherited from the sklearn.tree.export_graphviz but has no effect in the code, simply because matplotlib does not manage this option.

Two possibility here

• rotate can be simply removed
• a warning is thrown when rotate is activated in plot_tree

I would be happy to propose a PR, just let me know which solution would be preferable

Steps/Code to Reproduce

See #13971

Versions

For scikit-learn >= 0.21:

[TomDLT]

I suggest a deprecation warning