Allow code imports from starlark files

Jedi uses the Python-builtin importlib library to discover source files from a module name.
Modifying importlib's allowed file extensions from jedi is easier than providing a patched builtin library.

jedi/inference/compiled/subprocess/__main__.py

@@ -18,6 +18,9 @@ def _get_paths():
 if sys.version_info > (3, 4):
     from importlib.machinery import PathFinder
 
+    import importlib
+    importlib.machinery.SOURCE_SUFFIXES.append('.star')
+
     class _ExactImporter(object):
         def __init__(self, path_dct):
             self._path_dct = path_dct