Implement Versioning

[mspaulik]

If a CADL model has a version then that should be handled by the CADL emitter to RDF.

This task should be implemented after the namespaces are supported.

To add versioning to the project you first need to install the package: npm install @cadl-lang/versioning --save

Once you've done that you can import it in your CADL file.

import "@cadl-lang/versioning"

using Cadl.Versioning;

@versioned(Versions) 
namespace mynamespace {

     model Person {
            @added (Versions.v2) name: string;
            @added (Versions.v3) age: numeric;
     }
}

enum Versions {
     "v1",
     "v2",
     "v3",
}

[mspaulik]

Do after ENUMS are done.