As done with Cinder backend, we need to provide the required bits to configure Swift as a backend for Glance.
As per [1] , given we need Swift credentials to interact with the service, the idea is to config it as part of multistore pointing to a Swift related secret.
We also need to double check we can provide multiple secrets (e.g. cinder + swift) and end up w/ a working service.

[1] https://docs.openstack.org/glance/latest/configuration/configuring.html?highlight=swift#configuring-the-swift-storage-backend