[pvr] properly select the hovered channel in the channel manager

Fixes #15473. The issue is that we don't consider an item in the list selected unless the arrow keys or page up/down is used. We don't recognize click events so without this it's not possible to use the channel manager dialog with a mouse.

The only question is if `ACTION_MOUSE_MOVE` is the best event to listen on? The original bug report mentioned that some other input methods are broken too, not just regular mouses.