application authorization for openstack provider

[zeph]

seems that the authorization to the openstack_cloud_provider is via username/password only,
while in an organization we really need to be able to use the application specific tokens

• https://registry.terraform.io/providers/rancher/rke/latest/docs/resources/cluster#openstack_cloud_provider
• https://rke.docs.rancher.com/config-options/cloud-providers/openstack

also to have a consistent single way of authenticating when using cdktf for example in combination with

• https://registry.terraform.io/providers/terraform-provider-openstack/openstack/latest/docs#application_credential_secret

(right now I have a project that has a mix of application and user credentials, which is quite inconsistent)