Provide an option to set the minWidth of the ComboBox Popup.

We can add one of the following options:

1) Add style props to the ComboBox popupSettings. This will allow the developer to set a custom min-width.

2) Provide an option that will set the minWidth to the same as the ComboBox width.

We try to cover the following case:

The Popup will auto grow based on the longest item, but its widht should not be shorted than the ComboBox.