[518440] Complete migration participant

In some cases, the diagrams containing "corrupted edge labels" have also
a corrupted layout, with some nodes with very huge {x, y} coordinates.
The migration participant now detects them and reset their location to a
more conventional location. These diagrams must be manually layouted
after, the documentation explains that.

Bug: 518440
Cherry-picked-from: 517437
Change-Id: Ic809c6f9357328174a9ac21bee4e818c0f19ab8b
Signed-off-by: Laurent Redor <laurent.redor@obeo.fr>
8 files changed