Bug encountered while testing for v2023.1 (see #410 (comment)).

Step to reproduce:

1. populate the input with an IDN domain such as réussir-en.fr
2. open the options
3. click on "Fetch NS from parent zone"
4. see the popup "No data found for the zone."

Expected behavior:
Data should be retrieved for the given zone.

I digged a little bit into this, and it looks like the Backend does not convert the input domain in lookup_delegation_data.

Should the client send a converted domain or should we let the Backend handle the conversion. Since the Backend can be used by multiple clients, I think the conversion should be done there. Maybe this issue should be moved in Zonemaster-Backend as well.