Bug 414356 - [Viewers] Add generics to the ListViewer

Generics are added to the ListViewer to provide a type safty use of
this viewer

This change depends on the changes from
https://git.eclipse.org/r/#/c/14941/

Change-Id: Ie9a8681ac99bc08303adf790a3902e9b3f945ce7
Signed-off-by: Hendrik Still <hendrik.still@gammas.de>