[422957] Remove DeprecatedIEditingSession

Change-Id: Ibdcdbb89c62a790a7a78cf93c046a5ed1ac0ff90
Signed-off-by: Pierre-Charles David <pierre-charles.david@obeo.fr>
[422957] Cleanup EditingSession

Remove references in comments to the removed DeprecatedIEditingSession
interface and also remove all the methods in EditingSession which only
existed to implement DeprecatedIEditingSession.

Change-Id: I2dd228cad89ec90f96c64ce31bf3ec374f5af125
Signed-off-by: Pierre-Charles David <pierre-charles.david@obeo.fr>