This commit adds a new dialog_widget.js file containing most
of the code of confirm_dialog.js with some minor changes and
changes confirm_dialog to be a wrapper around dialog_widget.js.
We pass 'is_confim_dialog' as true in dialog_widget for a
confirm_dialog modal. This commit also renames confirm_dialog.hbs
and confirm_dialog_heading.hbs to dialog_widget.js,
dialog_widget.hbs and dialog_widget_heading.hbs respectively.
sahil839