- the tests here were no longer relevant because they were more testing
things that have been moved to `mailgun-client`
- this commit cleans up the tests to ensure we're passing the correct
parameters to the mailgun client package
- also adds jsdoc on all the functions and maintains 100% code coverage
refs https://github.com/TryGhost/Toolbox/issues/363
- this commit pulls all code involving the Mailgun client SDK into one
new package called `mailgun-client`
- this means we should be able to replace `mailgun-js` (deprecated) with
`mailgun.js` (the new, official one) without editing code all over the
place
- this also lays some groundwork for better testing of smaller
components
closes: https://github.com/TryGhost/Ghost/issues/14640
- eu mailgun domains have a different structure.
- we weren't accounting for this when fetching the next page of results, meaning that email stats didn't work on EU domains
refs https://github.com/TryGhost/Ghost/pull/12541
- make `EventProcessor` a super-class designed to be inherited from in consumer applications for application-level implementation
- helps to keep application-level concerns for event handling (eg, what to do with spam complaints) and things like application database knowledge in the consumer
- removed all database knowledge from `EmailAnalyticsService`
- requires a `queries` option to be passed in that lets the consuming application provide knowledge and define how fetched stats should be aggregated
