♻️(backend) rely on set_role_to from DocumentAskForAccess abilities

Like in other abilities, we compute a set_role_to property on the
abilities. This set_role_to contains all the roles lower or equal than
the current user role. We rely on this propoerty to validate the accept
endpoint and it will be used by the front allpication to built the role
select list.

src/backend/core/models.py

@@ -1205,23 +1205,14 @@ class DocumentAskForAccess(BaseModel):
 
     def get_abilities(self, user):
         """Compute and return abilities for a given user."""
-        roles = []
+        user_role = self.document.get_role(user)
+        is_admin_or_owner = user_role in PRIVILEGED_ROLES
 
-        if user.is_authenticated:
-            teams = user.teams
-            try:
-                roles = self.user_roles or []
-            except AttributeError:
-                try:
-                    roles = self.document.accesses.filter(
-                        models.Q(user=user) | models.Q(team__in=teams),
-                    ).values_list("role", flat=True)
-                except (self._meta.model.DoesNotExist, IndexError):
-                    roles = []
-
-        is_admin_or_owner = bool(
-            set(roles).intersection({RoleChoices.OWNER, RoleChoices.ADMIN})
-        )
+        set_role_to = [
+            role
+            for role in RoleChoices.values
+            if RoleChoices.get_priority(role) <= RoleChoices.get_priority(user_role)
+        ]
 
         return {
             "destroy": is_admin_or_owner,
@@ -1229,6 +1220,7 @@ class DocumentAskForAccess(BaseModel):
             "partial_update": is_admin_or_owner,
             "retrieve": is_admin_or_owner,
             "accept": is_admin_or_owner,
+            "set_role_to": set_role_to,
         }
 
     def accept(self, role=None):