fix #10018 fix #11945 - Improve relation member conflict resolution when combining ways
Keep/delete decisions are made if every member has the same role and the members are in consecutive order within the relation.
Moves CombinePrimitiveResolverDialog#prepareDefaultRelationDecisions to RelationMemberConflictResolverModel#prepareDefaultRelationDecisions.
CombinePrimitiveResolverDialog#prepareDefaultRelationDecisions
RelationMemberConflictResolverModel#prepareDefaultRelationDecisions