* Adds section and subsection library pages.
* Refactors routing to support them and fix routing from collections page to other pages.
* Refactors library context to reliably set component, unit, and other container ids even when the url changes when user goes back in history rapidly.
* feat: enable the problem editor for library components
* fix: don't try to load "advanced settings" when editing problem in library
* fix: don't fetch images when editing problem in library
* docs: add a note about plans for the editor modal
* fix: choosing a problem type then cancelling resulted in an error
* chore: remove unused mockApi, clean up problematic 'module' self import
* test: update workflow test to test problem editor
* feat: show capa content summary on cards in library search results
* docs: fix comment typos found in code review
* refactor: add 'key-utils' to consolidate opaque key logic
