Include module path / import specifier in output

[justinfagnani]

In order to use an element you need to know what module to import. The custom-elements.json output doesn't include this at the moment.

[bahrus]

It would be nice if the "path" could be overridden by a JSDoc setting on the class.

The purpose is doing that is I'm using a derived class so I can set default values, so the analyzer picks up on the properties. But I want the output custom-elements.json file to contain the path to the base class, not the derived class.