Document dashboard integration

Marking as draft until required backend work is complete. Also note that the base branch is blms/project-dashboard-integration.

In this PR

• Document dashboard integration
  • For more details, see individual commit messages. They are broken down by topic.

Required backend work

• Per-document regions and lines ontology endpoints, each with count, and OrderingFilter on count and name
• Also need the count and OrderingFilter on AnnotationTaxonomySerializer
• Share endpoint for documents (share with group or user)
• (Possibly) some work on the tasks endpoint, see below

Questions

• A handful of issues with task reporting:
  • Seems like there's some document tasks that aren't getting properly assigned to the document pk. Any idea why? (see #913 (comment 1523351159))
  • Can we improve some of the string representations of tasks? Or do you have ideas for how I could handle the api response better?
  • Looks like we're now doubling the alerts. How should we handle during the transition period? (see #922 (comment 1540204245))
• Do we need access to ALL models for segment and transcribe, or just document models? I'm assuming the former, and included code for that, but wanted to double check.
• @Lauxley you asked earlier about the "only recalculate masks" option. Chelsea and I believe the decision was that masks are always recalculated. Does that sound right?