This increases the time to list apps from .05s to .2s~.3s on the simplest check, but the increased time is worth it for actually verifyng access to an app (should that need arise).
We'll also want to add the same to app existence checks.
This ensures the value is correct, where previously it was computed based on a file - and therefore did not distinguish between git:from-archive and git:from-image.
Closes#4464
