possibility to call module from registry with version stored in variable

**Is your feature request related to a problem? Please describe.**
Now it is not possible to call a module from registry with specified version in a variable

```
var version = '0.0.1'
module mod_webapp 'br/CoreModules:mod_webapp:${version}' = {
name: 'deployment-mod_webapp'
...
}
```

**Describe the solution you'd like**
I would like to store the module version in the variable or param.

The issue names no files, tests, or entry points; start by locating the Bicep code that parses module registry references and handles version expressions. Confirm the desired behavior for a variable or parameter holding the version, then add coverage showing that the registry module reference resolves with that value.

Written by the indexing model from the issue text.