`Library` response always returns empty lists for top level `variables` and `functions`

A full `Library` response should include references for any top-level classes, fields/variables, and functions that are included with the library. Currently dwds doesn't populate the `variables` and `functions` properties of `Library`.

This can be easily reproduced by requesting the `Library` which contains `main()`, which should be included in the `functions` list.

This blocks the program explorer work.

Start by locating the code that builds the Library response in dwds and trace how the library containing main() is represented. Reproduce the request described in the issue and inspect the existing top-level class, field, variable, and function references. Done means the variables and functions properties include the corresponding top-level declarations, including main(), so the program explorer can use them.

Written by the indexing model from the issue text.