WIP: Backport functional test and developer sandbox changes to tracker-2.3 branch
These patches have improved the developer experience for me a lot in the 'master' branch. It'd be useful to have all these changes on the 2.3 branch too which we'll be maintaining for a long time.
Marked as WIP as I'm not sure if we should actually release all this stuff in a bugfix 2.3.x release.
Edited by Sam Thursfield