[domains] Display the ACME challenge in case of wildcard domain

[EtienneM]

When adding a wildcard domain (https://doc.scalingo.com/platform/app/domain#wildcard-domain) to an application, one need to update the TXT DNS record every three months. The value that the customer needs to set is displayed on the dashboard, but not on the CLI:

❯ scalingo --app my-app domains
+---------------+---------+
|    DOMAIN     | TLS/SSL |
+---------------+---------+
| *.my-domain.fr | -       |
+---------------+---------+

Whereas on the dashboard:

The needed values are available in the response of the request GET /v1/apps/my-app/domains, in the fields acme_dns_fqdn and acme_dns_value.

Related to https://app.intercom.com/a/inbox/w4oogu7s/inbox/admin/524634/conversation/12375700229320?view=List