demos: Refactor tool groups to be re-usable between toolbars
demos: Refactor tool groups to be re-usable between toolbars

Factor out creation of toolgroup with a toolbar from the definition
of the tools so that we can re-use the same list in multiple places
and reduce duplication that way.

Also:
* Add a bunch more tools to the "listTools" group to make it easier
  to demonstrate behaviour of clippable element in case a dropdown
  menu touches the bottom and/or right edge of the window.

Change-Id: Id9cd6d32df00b23ea95b2fea85651492e299581f

wikimedia/oojs-ui,wikimedia/oojs-ui,wikimedia/oojs-ui,wikimedia/oojs-ui