Introduce recursion=2 for storage volumes and storage buckets

[breml]

What are you currently unable to do

Get storage volume and storage bucket details including snapshot and backup information, similarly to how it is possible for instances with client.GetInstanceFull.

What do you think would need to be added

Introduce recursion=2 with ...Full struct for storage volumes and storage buckets.
Add the respective methods to Incus client package.