[427803] Correct Split merge side effects

The AirNoteAttachmentEditPolicy and AirNoteAttachmentEditPolicyProvider
have been initially removed in commit
8db397b66ee5479a5613d5987663589e14128510 but during the diagram split
they were moved to the diagram.ui plugin and the merge commit
f47d4f72102a795cedc92334593480d56d72b44d was not able to delete the
moved corresponding classes.

Bug: 427803
Change-Id: I398e3d59039d22f5fd253ab3df3bd003c7946568
Signed-off-by: Maxime PORHEL <maxime.porhel@obeo.fr>
[427803] Correct Split merge side effects

The AirNoteAttachmentEditPolicyProvider declaration in diagram.ui
plugin.xml was reintroduced in the merge commit too. It has been
intially removed in commit
8db397b66ee5479a5613d5987663589e14128510 but during the diagram split
it was moved to the diagram.ui plugin and the merge commit
f47d4f72102a795cedc92334593480d56d72b44d was not able to delete the
correcponding extension.

Change-Id: Ibb6f11cf34c550324465f155b057654945c5420d
Signed-off-by: Maxime PORHEL <maxime.porhel@obeo.fr>
[cleanup] Update javadoc of FileHandledBySessionTester

Change-Id: I73630f449b8440d51b7223f6116de3ec7cb89159
Signed-off-by: Laurent Redor <laurent.redor@obeo.fr>