[eclipse-pmc] API request: add new methods to AbstractTableViewer and St

[Boris Bokowski <Boris_Bokowski@xxxxxxxxxx>]

REQUEST:

We would like to add API to StructuredViewer,
AbstractTableViewer, and TableViewer to fix a long-standing bug that caused
setSelection() to always scroll to the selection even if the reveal parameter
was false.  The bugfix requires additional API on AbstractTableViewer
so that we can make the fix in the widget-independent layer (AbstractTableViewer)
instead of just fixing it for TableViewer, and additional API on StructuredViewer
so that clients calling preservingSelection() can make use of the fixed
behaviour.

BUG:
https://bugs.eclipse.org/bugs/show_bug.cgi?id=164796

RISKS:
None, the only subclass of AbstractTableViewer
we know of is part of Nebula and we are coordinating this change with them.

PERFORMANCE IMPLICATIONS:
None

Thanks,
Boris.