[429682] Remove Mapping.IS_CHECK_ONLY predicate

Avoids a reference to Guava-specific API.

Bug: 429682
Change-Id: I93b15ace04bb092bab2406ef5ae258e678086556
Signed-off-by: Pierre-Charles David <pierre-charles.david@obeo.fr>
[429682] Remove Maybe class, replaced by Option

The MaybeFactory exposed a Guava function, but instead of simply
removing the method, replace the whole Maybe and MaybeFactory classes
defined in org.eclipse.synchronizer by the equivalent Option and
Options types.

Bug: 429682
Change-Id: I33c2d1c380f9d241199e47e9c6aa98ca1667e1c7
Signed-off-by: Pierre-Charles David <pierre-charles.david@obeo.fr>
[429682] Remove the unused SiriusFunctions class

It exposed a Guava-specific Function type, but was not actually used
anywhere.

Bug: 429682
Change-Id: Ifbdf788c487baaece42203e41126d9b4a5021f0f
Signed-off-by: Pierre-Charles David <pierre-charles.david@obeo.fr>
[cleanup] Remove oes.diagram.sequence.util.NotificationQuery

Change-Id: I170d08d9dce7728b3b21b754edd5985ae6c23c76
Signed-off-by: Pierre-Charles David <pierre-charles.david@obeo.fr>
[429682] Remove oes.sequence.util.NotationPredicate from APIs

It exposed a Guava-specific type, and was only used in a single internal
package, so it was moved there.

Bug: 429682
Change-Id: Ib562f1114aef46865fbe819020b2c88528ea492c
Signed-off-by: Pierre-Charles David <pierre-charles.david@obeo.fr>