TEIIDDES-1947: Adds workaround for Group layout issues

* There appears to be a bug in the SWT Group widget where dialogs are not
  layed out correctly when first displayed. If the Group has a title, the
  group's content overlaps it and likewise can sometimes be truncated at
  the bottom.

* WidgetFactory
 * By setting the top margin to a value of '10' the overlapping and
   truncation is removed. However, in some cases the margins are correctly
   observed hence a 10 point gap is displayed under the group title. Thus,
   this remains a workaround and not a complete solution.

* Where components make use of WidgetFactory.createGroup, ensures that they
  do not override the layout.