Insights/api/dashboard migrate

Created by: coury-clark

Closes #25659 (closed)

Adds a background job to migrate dashboards to the new database tables in a similar manner to how insights are migrated. The job executes in the same context (same time / interval) and will try and migrate any dashboards found in settings.

Currently this will only link up insights that are backend compatible, as they are the only ones that will be found when attempting to link by ID.