Feat req: Add OpenStack Object Storage

[lcmgh]

Hi! I'd love to see support for OpenStack's Object Storage. https://docs.openstack.org/security-guide/object-storage.html

Might the following be a workaround? Multi-attached volumes (https://registry.terraform.io/providers/terraform-provider-openstack/openstack/latest/docs/resources/compute_volume_attach_v2) + CACHEPOT_DIR that points to the shared volume