Finishes refactoring libraries APIs [FC-0083] (openedx#36468)

Addresses libraries API TODOs introduced by openedx#36371

Author: pomegranited

openedx/core/djangoapps/content_libraries/api/__init__.py

@@ -1,7 +1,10 @@
 """
 Python API for working with content libraries
 """
+from .collections import *
 from .containers import *
+from .courseware_import import *
+from .exceptions import *
 from .libraries import *
 from .blocks import *
 from . import permissions