Snoop: improve options for the code generation client command

The tool is not intuitive when it comes to specifying some options in the code generation. The default mode generates floating-point code and fixed-point code is generated if --fixed-point parameters-json is passed; there’s no way to use the default parameters without copying them back in a json.

The UX should be improved, possibly by providing a way to export default parameters to allow user modifications, or giving more ways to specify the desired parameters.