Support clouds.yaml cacert file

[alexandrevilain]

/kind bug

What steps did you take and what happened:

clouds.yaml has a cacert key referencing a path to a ca certificate file. For now, the provider doesn't use this ca certificate when defined.

What did you expect to happen:

Creating a cluster with the following clouds.yaml file should work if file provided in clouds.openstack.cacert exists.

clouds:
  openstack:
    auth:
      auth_url: "HIDDEN"
      username: "HIDDEN"
      password: "HIDDEN"
      project_id:"HIDDEN"
      project_name: "HIDDEN"
      user_domain_name: "Default"
    cacert: /etc/ssl/certs/ca-certificates.crt
    region_name: "HIDDEN"
    interface: "public"
    identity_api_version: 3

Anything else you would like to add:

The field is supported by gophercloud: https://pkg.go.dev/github.com/gophercloud/utils/openstack/clientconfig#Cloud

Environment:

• Cluster API Provider OpenStack version (Or git rev-parse HEAD if manually built): v0.6.4
• Cluster-API version: v1.3.1
• OpenStack version: N/A
• Kubernetes version (use kubectl version): 1.25
• OS (e.g. from /etc/os-release): ubuntu 22.04

[alexandrevilain]

Closing in favor of #1439