refs: https://github.com/TryGhost/Toolbox/issues/168
- These are all places where we reference an API version like v2 or v3 but it's not actually
used or relevant.
- The aim is to get rid of all mentions of these old versions to make it clearer that we're only running tests on canary
- move all test files from core/test to test/
- updated all imports and other references
- all code inside of core/ is then application code
- tests are correctly at the root level
- consistent with other repos/projects
Co-authored-by: Kevin Ansfield <kevin@lookingsideways.co.uk>