Update the extract_package_code to work both installed packages and package sources

[fikovnik]

It should support two use cases:

• extracting code from installed package

  extract_package_code(package, lib_paths, ...)

  looking for package in lib_paths

• extracting code from package sources

  extract_package_code(path, ...)

  which will first install the package into a temp dir and then extract the code