- Refactor `ShowDocumentInfo`: don't link to documents for third-party
  annotations. This is a possibly-temporary measure to prevent linking
  to documents that are not directly accessible, e.g. in an LMS context.
- Remove unnecessary forwarding of `showDocumentInfo` through several
  components.
- Centralize some logic in `AnnotationHeader` and make `ShowDocumentInfo`
  a dumb component.