refactor: Split base.in into kernel.in (required) and bundled.in (optional) (#32552)

Plus remove a few unused and indirect dependencies

xmodule/modulestore/tests/utils.py

@@ -2,13 +2,12 @@
 Helper classes and methods for running modulestore tests without Django.
 """
 import os
-from contextlib import contextmanager
+from contextlib import contextmanager, ExitStack
 from importlib import import_module
 from shutil import rmtree
 from tempfile import mkdtemp
 from uuid import uuid4
 
-from contextlib2 import ExitStack
 from path import Path as path
 
 from xmodule.contentstore.mongo import MongoContentStore