[Feature Request] Can we make select on change for cascader single selection more user friendly

### Existing Component
是

### Component Name
cascader

### Description
When single selection and selection on change is turned on for cascader, one can select arbitrary level node by clicking the left side radio button of the cascade node, and expand the next level menu by clicking the label right after the radio button, but it is not very user friendly, since if people want to select the middle level node, the click area is very limited to the radio button area (a very narrow space).

Is that possible to add an option to enable the middle level selection even when click on the right side label? when clicking right side label, the behavior could be: the node is selected, and the next level menu is also expanded.

This would make choosing the middle level cascade node easier.