TNL-930: Turn off Student Notes when Harvard Annotation Tool is enabled.

Disables Student Notes if one of `textannotation`, `imageannotation`, `videoannotation` modules exist in the list of `Advanced Modules`.

There is still possibility to break `Student Notes` and `Harvard Annotation Tool`:
  - add one of `textannotation`, `imageannotation`, `videoannotation` to the `Advanced Modules` list;
  - add one of `textannotation`, `imageannotation`, `videoannotation` to the unit;
  - remove it form the `Advanced Modules` list => **You can enable Student Notes now. If you have both modules in the sequential, it breaks one of these modules.**

I think we should write a good note about this situation.

@tymofij , @olmar, @jmclaus, @srpearce  please review.

**sandbox:** http://studio.polesye.m.sandbox.edx.org/
> what do you think about just using Harvard's notes.utils.notes_enabled_for_course for checking?

It doesn't check for 'textannotation', 'imageannotation', 'videoannotation' fields. So, we cannot use it.