Deploy pushed development images automatically via Argo Image Updater

[spwoodcock]

• Related to Use ArgoCD ApplicationSet to deploy staging environments on demand via PRs #32, which will handle stage.
• For dev, we can probably just run an on-prem cluster or some other cheap solution.
• Ideally ArgoCD in that cluster (or flux image reflector) can scan the image registry for new dev images, and simply deploy them as they are made available.
• This prevents needing to manually deploy dev setups, instead having a true (CI/)CD approach to development.