A bulletproof `wait_for_turbo` test helper

I like Hotwired Turbo like I liked UJS (Unobtrusive Javascript): it adds a few small but helpful tricks to my application’s toolbox. One problem though with adding any javascript is that because the webpage is more dynamic, writing full-browser system tests becomes harder because we need to make sure the webpage is in just the right state to interact with it in tests. It’s annoying to write tests…