Fix The corpus set operators commands
- add the commands in corpora view contextual menu
- linux : the subcorpus list does not show the subcorpora
- UNION and INTERSECTION : stop if the selection has not 2 subcorpus selected
Names :
- MINUS ->Substract / Soustraire
- INTER ->Intersect / Intersection
- UNION ->Add / Ajouter
(from redmine: issue id 3206, created on 2022/01/14 by Matthieu Decorde)