Extended modalPopup.js to support specifying keyboard shortcut options for the defined actions

Currently, when creating or extending an XWiki ModalPopup widget, you can register keyboard shortcuts, but you are not able to provide options for those shortcuts.

An example is jumpToPage.js where you need to specify that some keyboard shortcuts should propagate, so that other contained widgets (like the suggest widget) might get the chance to handle the (Enter or Escape) keyboard event that was triggered on the text input.