Hide annotations that are outside of assignment page range

[robertknight]

When the user is in an LMS assignment with a configured page range, annotations from outside of that range should be hidden by default.

In the case where the same book is being reused for multiple assignments, this will avoid showing annotations from one assignment while viewing another.

This issue may become obsolete pending developments in a more general discussion about filtering annotations by assignment + document rather than just by document in the LMS context.

[robertknight]

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).

[robertknight]

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

[robertknight]

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.