Add `npm run seed` to CI/CD

[krubenok]

With @pierreTklein's work on restoring confidence in the npm run seed command (#652, pending a successful manual deployment). I believe we should work to automate the database readiness steps involved in promoting new versions of the API to production.

I propose adding a Github Actions workflow that will do the following:

1. SSH into a server to create a mongodump snapshot of the production database and report back the integrity of the backup.
2. Run npm run seed on the production database
3. Report back into the team Slack with references to these events.

[loreina]

dup: #660. will fit this into transition to Github Actions, thanks @krubenok :)