Improve support for System Composer in the Simulink driver

[kolovos]

As the Simulink driver doesn't provide dedicated support for System Composer, one would need to use its fallback statement and statementWithResult methods. For instance, to create a small system composer model one could replace the body of the EOL program in this example with the following.

M.statement('model = systemcomposer.createModel("archModel")');
M.statement('systemcomposer.openModel("archModel")');
M.statement('arch = get(model,"Architecture")');
M.statement('variant = addVariantComponent(arch,"Component1")');
M.statement('compList = addChoice(variant,["Choice1","Choice2"])');

In the future it would be useful for the driver to provide a more natural way of working with System Composer models.