Deployment from private registries

**Is your feature request related to a problem? Please describe.**
With private registries, we've got these great centralized stores to which we can upload our versioned templates to consume as modules in still other templates. Maybe this is possible today and the documentation just hasn't caught up, but it'd be amazing to be able to similarly deploy directly off these private repositories as opposed to keeping non-centralized module copies in our various CI/CD pipelines and simply pass our various parameters as part of a New-AzResourceGroupDeployment operation, passing in the 'br' path to the repository instead of a local template file.

Alternatively, in the shorter term, offer an opposite option to `bicep publish` that easily lets me retrieve the template from the ACR store so I can temporarily store it locally to pass into the method myself.

**Describe the solution you'd like**
In order of what I'd prefer to see:
1) Bicep command to deploy from module registry
`bicep deploy -path "br:abc.azurecr.io/bicep/modules/myapp:v1.0"` -resourceGroup "MyResourceGroup"

2) Update to RG deployment script to use registry path instead of local template path
`New-AzResourceGroupDeployment -ResourceGroupName "MyResourceGroup" -RegistryPath "br:abc.azurecr.io/bicep/modules/myapp:v1.0"`

3) Download from published ACR instance to local file, then deploy: `
bicep download -path "br:abc.azurecr.io/bicep/modules/myapp:v1.0" -localPath "myapp.bicep"
New-AzResourceGroupDeployment -ResourceGroupName "MyResourceGroup" -TemplatePath .\myapp.bicep
`

Start by reviewing the existing bicep publish flow and the documented New-AzResourceGroupDeployment entry point. Compare the three requested paths—bicep deploy, registry-backed RG deployment, and bicep download—and identify the deployment and ACR integration points that would need ownership and design decisions. Done means selecting and implementing a scoped approach with coverage for private registry templates.

Written by the indexing model from the issue text.