Create a report for document sources

Generate a question(s)/dashboard to explore how different document sources are used in LMS.

The goal is to join this data with annotation to get a good idea of usage per document type.

However we can initially base the number in the number of assignments created, later in the number of launches for those assignments and finally joining with annotations in the final version.

- [ ] Overall number of assignments per source over time(by number of assignments created)
- [ ] Popularity of sources in a given organization sources over time (by number of assignments created)
- [ ] Number of launches per source
- [ ] Number of annotations per source?
- [ ] Link the filtered by org question from the org dashboard.

[WIP question in metabase](https://report.hypothes.is/question/242-wip-document-sources?period=month)

Technical tasks:

- [ ] Upgrade metabae to the newest version (we are in 45, latest is 49). It does have a bunch of improvements to dashboards etc.
- [ ] Include new sources in the report. Moodle, Canvas Studio, Canvas Pages are missing.
- [ ] Include `document type` as a concept in the LMS code base. To avoid having that awful case statement in the queries.