Remove need for a password when deploying container image from Azure Container Registry

**Is your feature request related to a problem? Please describe.**

When creating a new deployment, or updating a deployment, for a container image hosted within Azure Container Registry into Azure Spring Apps, a registry username and password must be passed in the az cli command line with the following parameters: --registry-username and --registry-password.

Reference: https://learn.microsoft.com/en-us/cli/azure/spring/app/deployment?view=azure-cli-latest#az-spring-app-deployment-create

We would like to avoid needing to use a password.

**Describe the solution you'd like**

Allow the use of a managed identity to connect to the container registry, or allow an access token to be passed similar to the ACR login command documented here - https://learn.microsoft.com/en-us/azure/container-registry/container-registry-authentication?tabs=azure-cli#az-acr-login-with---expose-token

**Describe alternatives you've considered**

There does not appear to be any other alternatives when running from the command line.

When running within a DevOps pipelines, store the password into Key Vault and setup the pipeline variables to read from Key Vault.

Though, this requires somebody to generate a password and put it into Key Vault.

**Describe the Customer Impact**

Would like to avoid the need for any password.

**Additional context**

It seems the password is required due to the Spring Apps API requiring it to be set within the imageregistrycredential as documented here - https://learn.microsoft.com/en-us/rest/api/azurespringapps/deployments/update?tabs=HTTP#imageregistrycredential

**Can we contact you for additional details?**

Yes.