[456771] Add SiriusFile.gif icon and update licence.txt files

This commit recreates the icon that have been removed in commit
cd558cb06d7807291a78def287f13647e37676ab.
We need to have this icon in org.eclipse.sirius.ui because it used
through SiriusEditPlugin.Implementation.getBundledImage(String) method.

Update licence.txt file for org.eclipse.sirius.ui and
org.eclipse.sirius.ui.ext according to the existing icons in project.

Bug: 456771
Change-Id: I26803991c0c557f6a04482b73201faa217792085
Signed-off-by: Laurent Fasani <laurent.fasani@obeo.fr>
3 files changed