Add support for other storage domain types

[JasonN3]

Right now DATA, ISO, and EXPORT are the only types allowed as storage domains. oVirt has since added more types.
Here's the full list from the go-ovirt repo:
STORAGEDOMAINTYPE_DATA
STORAGEDOMAINTYPE_EXPORT
STORAGEDOMAINTYPE_IMAGE
STORAGEDOMAINTYPE_ISO
STORAGEDOMAINTYPE_MANAGED_BLOCK_STORAGE
STORAGEDOMAINTYPE_VOLUME

Even if it take a while to fully support it as a resource, supporting it as a data source would be beneficial.

[ghost]

Hello @JasonN3 thank you very much for your request. We are moving the Terraform provider to a new backend which supports these storage domain types. Once this move is complete the new storage domain types should automatically be supported.