TNL-932: Add styling to Notes page.
TNL-762: Add course structure view.
uncached version of notes structure
Update frontend.
Display course structure tab.
Cleanup.
Add jasmine tests.
Improve memory usage.
Update js tests.
Update helpers.
Update js tests.
Add bok-choy tests.
Add fixes.
Add python unit tests.
Update course structure view.
Fix bok-choy tests.
Fix import.
Add comment.
Fix unit tests.
make block.get_parent() work.

Co-Authored-By: Christina Roberts <christina@edx.org>
Co-Authored-By: Daniel Friedman <dfriedman@edx.org>
Co-Authored-By: Don Mitchell <dmitchell@edx.org>