Do cli 2.0 allow image host not under "mcr.microsoft.com"?

## Which example? Describe the issue

example:

Host of image is under mcr.microsoft.com
> $schema: https://azuremlschemas.azureedge.net/latest/environment.schema.json
name: docker-image-plus-conda-example
image: mcr.microsoft.com/azureml/openmpi3.1.2-ubuntu18.04
conda_file: conda-yamls/pydata.yml
description: Environment created from a Docker image plus Conda environment.

Host of image is not under mcr.microsoft.com
> $schema: https://azuremlschemas.azureedge.net/latest/environment.schema.json
name: docker-image-plus-conda-example
image: viennaglobal.azurecr.io/azureml/azureml_fea03cf22bb20f3ab9b04972a025e9d3
conda_file: conda-yamls/pydata.yml
description: Environment created from a Docker image plus Conda environment.

description:

Sometimes I want to create customized environment by using the curated environment as my base image.
Can I replace image like this screenshot environment "viennaglobal.azurecr.io/azureml/azureml_fea03cf22bb20f3ab9b04972a025e9d3" ?

HOW can I set the curated environments container registry as my base image that registry is not under "microsoft.com" ?

## Additional context

-

Start with the Azure ML environment.schema.json reference and the example using conda-yamls/pydata.yml, then investigate how Azure ML CLI 2.0 handles image registry hosts. Done means establishing whether a curated environment image from viennaglobal.azurecr.io can be used as a base image and documenting or demonstrating the supported configuration.

Written by the indexing model from the issue text.