Fix infinity-loader not updating model when infinity reached

[robinborst95]

Reason

In our application we allow changing filters that are passed to the infinity model, so we create a new infinity model. However, when the current model has reached infinity, updating the infinity model does not update within the infinity loader, so the new model does not load more pages.

I added a test that reflects this, and fixed it by adding an empty div when not shown, to host the {{did-update}}. Not an ideal solution, so let me know if there are other solutions 👍

[MelSumner]

I don't know what else to suggest but I can at least help you get unblocked with this workaround if that's useful.

Adding for clarity: obviously we don't want to use {{did-update}} but it's already being used in this addon, so there's no sense in keeping you blocked while the addon is updated. I'm going to file an issue so this addon can be evaluated for further updates or maintenance.