Enhancement: add support for /api/v1/self-service/settings, /api/v1/self-service/branding/macos and /api/v1/onboarding

[ecanault]

Hi,

The endpoints /api/v1/self-service/settings, /api/v1/self-service/branding/macos and /api/v1/onboarding exist in the SDK but not yet in the provider.

These endpoints, including /api/self-service/branding/images (#516) will permit to fully manage macOS Self Service with Terraform.

By the way, knowing that Self Service + is in the pipeline, perhaps it will be better to wait for this new release.

Thanks,
Emmanuel