Provide options to alignment and auto fit for bar items Validated

As per the current behavior of bar items, we do not have an option to change the alignment of bar items. Also, the bar items will be displayed with only the constant width given at the initialization and it leaves the extra space of toolbar as empty space. For example, if the toolbar contains two bar items and one is textbox bar item and another one is empty bar item. In this case, expect the text box bar item, remaining spaces will be leaved as empty. Hence we need to provide the support to automatically occupy the width from toolbar for bar items with the help of Autofit property. Also, we need to provide the support to set the align the bar items either horizontally or vertically.