Hide annotations that are outside of assignment page range about client HOT 3 CLOSED

A complication with this is that annotations created on EPUB-based books do not currently record page number selectors, so if the assignment range is expressed as a page range, rather than a CFI range, we cannot filter annotations against it them.

Some things we can do:

1. Start record page number selectors for all annotations, whether the book is PDF or EPUB-based. An issue with this is that we won't have these selectors for existing annotations.
2. Map the CFI for each annotation to a corresponding page number. We might be able to do this with the data that VS exposes to our code. A downside is that we won't have access to this information outside the context of the assignment (eg. in a future iteration of the notebook).

from client.

This will be basically working once hypothesis/lms#5930 lands, with UI improvements to follow (see #6006).

from client.

I'm marking this as done. Making toggling the visibility of annotations outside the page range more usable is necessary though and is covered by #6006.

from client.