Easy way to identify all experiences where VEC selectors have changed

[#1]

It's impossible for us to keep on top of CMS changes, and when using the VEC this can have wildly unexpected results when a change occurs to the page and the content authors can't test the page against all experiences being applied to the page.

In the activity list/browser, we should have an easy way of identifying all active activities where the VEC is in use and there has been a change to the page/selectors and re-validation or adjustment is required. Alerts would also be highly useful.

[#2]

This is a very useful feature request. We have been struggling with the CMS changes in our multi-brand environment and it is a pain to identify those activities which have stopped delivering the experience due to the DOM elements changing on site. 

One easy way to track could be to detect drastic difference in metrics (engagement / clicks etc.) due to any site changes. Then  immediately send a trigger pointing out the anomaly.