[feature] Visual Selector - offer to "just tell me when this text is no longer on the page" filter

Very often I can see that people are using the visual selector to follow some HTML element, but then what happens is that the page will change structure (like when the website has more stock available) and then the element they have clicked on can no longer be found by the automatically generated xPath

What would be better is to have the visual selector ask "Should I alert you when this text is no longer present on the page?" instead of locking in a very fragile xPath filter

for example. people use the VisualSelector for choosing the element of

Start with the visual selector and XPath scraper entry points, then trace how generated XPath filters are offered for selected elements. Review the existing restock detector behavior and determine how a unique text value could be identified and presented as an alternative. Done means the selector can offer text-presence monitoring for uniquely matching text without disrupting the existing XPath flow.

Written by the indexing model from the issue text.