Show sandbox access

Since we can't guarantee the level of sandboxing for flatpaks from outside AppCenter, I think it makes sense to show what kind of install time permissions will be granted.

The expectation that we want to trend towards in AppCenter is active consent over portals. So if a user assumes that every app they install *must* ask for permission to use Location or to capture the screen, but this sideloaded app doesn't have that kind of sandboxing, that's important to know.