[457034] ProximityEObjectMatcher should support cancellation

Improved monitoring by making use of SubMonitor and supporting
cancel where it makes sense.
Also added dedicated unit tests.
Didn't want to break the API so added TODOs instead...

Bug: 457034
Change-Id: I92dc82e2217c0cce818fb3d95a545f38f97bc86b
Signed-off-by: Laurent Delaigue <laurent.delaigue@obeo.fr>
18 files changed