xenorchestra_vdi data source implicitly requires pool_id

[ddelnano]

After debugging the following situation with a user in discord (link), I realized that the xenorchestra_vdi data source implicitly requires a pool_id argument. The problem is this code here that only allows VDI objects to match by name_label if the pool_id matches as well.

This is confusing since the documentation states that filtering by name_label alone should work as long as there aren't multiple results returned. We should see if its possible to fix the logic in the VDI.Compare method.