Move service feedback Performance Platform stats upload from the 'support' app

The `support` app is being split into a frontend-only component and an API component (this app). Part of this work is moving the Performance Platform stats upload batch job.

This code has been lifted from the `support` app (it's functionally identical), and will be removed from the `support` app once this change is deployed.
If you want to be able to deploy this to preview and have a separate queue from support's existing one, then you'll need to set a different namespace here - I ran into this a couple of days ago when deploying Transition's postgres-master branch to preview alongside normal transition. If the namespace is the same, then workers from both apps will be sharing the same queue.