title: Authenticate Azure ContainerRegistryClient with scope maped token username/password?
body: <p><code>Azure.Containers.ContainerRegistry.ContainerRegistryClientOptions</code> has a parameter <code>credentials</code> that accepts any <code>TokenCredential</code> instance. There is a long list of options available, but all lead to actual Azure AD credentials. Even the username/password type is actually the username/password of an Azure AD user</p>
  <p>Is there a way to provide the user/password combo one would use when using the (in preview) feature of ACR scoped tokens (which is effectively &quot;users for ACR&quot;), or is this SDK only intended for apps that have a managed identity? For username/password API access, would we then need to user a .NET SDK around the Docker API?</p>
  <p>thanks in advance</p>