AccordionContainer no onHide function called on children

[jfcunat]

When you change of pane in a AccordionContainer?, there is a call to show the new child but no call to hide the old one.

In the overriden function _transition of the AccordionContainer?, only the _showChild is called (and the onShow method on the child if it exists). The _hideChild is not called (and not the onHide of the child). Is there any reason ? In the ancestor this method _hideChild is called.

We rely on this method to deactivate some features of our components when they are hidden in a layout widget.

I give a patch to add the call in the OnEnd? of the animation of onHide if the widget has this function

[Adam Peller]

(In [16875]) Fixes overlapping accordion transitions, call onHide. Thanks jfcunat for the great patch! Fixes #8788, #8787.