🐛(backend) fix invitations API endpoint access rights

Only users who have the rights to manage accesses on the document should
be allowed to see and manipulate invitations. Other users can see access
rights on the document but only when the corresponding user/team has
actually been granted access.

We added a parameter in document abilities so the frontend knows when
the logged-in user can invite another user with the owner role or not.

src/backend/core/api/viewsets.py

@@ -807,7 +807,10 @@ class InvitationViewset(
 
     lookup_field = "id"
     pagination_class = Pagination
-    permission_classes = [permissions.IsAuthenticated, permissions.AccessPermission]
+    permission_classes = [
+        permissions.CanCreateInvitationPermission,
+        permissions.AccessPermission,
+    ]
     queryset = (
         models.Invitation.objects.all()
         .select_related("document")
@@ -842,10 +845,16 @@ class InvitationViewset(
             )
 
             queryset = (
-                # The logged-in user should be part of a document to see its accesses
+                # The logged-in user should be administrator or owner to see its accesses
                 queryset.filter(
-                    Q(document__accesses__user=user)
-                    | Q(document__accesses__team__in=teams),
+                    Q(
+                        document__accesses__user=user,
+                        document__accesses__role__in=models.PRIVILEGED_ROLES,
+                    )
+                    | Q(
+                        document__accesses__team__in=teams,
+                        document__accesses__role__in=models.PRIVILEGED_ROLES,
+                    ),
                 )
                 # Abilities are computed based on logged-in user's role and
                 # the user role on each document access