Fix non default tenant and HTTPS support

Using Bosch IOT Rollout server implies to use a specific tenant, which currently fails with message 401 Unauthorized.
Setting tenant to another value then DEFAULT is not used.

HTTPS artifact URL is provided in download entry, while HTTP one is provided in download-http. Add HTTPS url support and try to use it in first intention.

Use g_autoptr for JSon builder, generator and node.

Signed-off-by: Frédéric Danis frederic.danis@collabora.com