volumes: volume_path field is not available

[denik]

${resources.volumes.foo.volume_path} is available in terraform but not in direct engine.

https://github.com/databricks/terraform-provider-databricks/blob/main/catalog/resource_volume.go#L105

Workaround is possible:

/Volumes/${resources.volumes.foo.catalog_name}/${resources.volumes.foo.schema_name}/${resources.volumes.foo.name}

but we should probably just support it natively.