no issue
- additional migration for the column added since the last 3.1 beta release to allow beta upgrades without rollbacks
- will be a no-op for upgrades from 3.0 as it's covered by `3.1/05-add-emails-table.js`
We want to allow admin users to trigger a retry of failed emails without having to go through the unpublish/republish dance.
- fixed resource identifier in email permissions migration so email permissions are added correctly
- added new email permissions migration so that beta releases can be upgraded without rollback (will be a no-op for any non-beta upgrades)
- added `/emails/:id/retry/` canary Admin API endpoint
- follows same URL pattern as theme activation
- only triggers mega service retry endpoint if the email has a `'failed'` status
