- this is a small part of a bit of cleanup of our test files
- the goal is to make the existing tests clearer with a view to making it easier to write more tests
- this makes the test structure follow the codebase structure more closely
- eventually we will colocate the tests as we break the codebase down further
refs https://github.com/TryGhost/Ghost/security/advisories/GHSA-wfrj-qqc2-83cm
refs https://github.com/advisories/GHSA-48ww-j4fc-435p
- a vulnerability in `nodemailer` means that the `sendmail` transport is
vulnerable to command injection for flags passed to the `sendmail`
binary
- updating to the latest version of Nodemailer required creating
`@tryghost/nodemailer`, which is a wrapper around Nodemailer and
several plugins that used to be in the core
- this commit switches to using that package, and fixes up some small
code + test changes