[feature] Re-stock & Price detection Regex/XPath/CSS selector

**Describe the solution you'd like**
Would be nice if we could declare a Regex/XPath/CSS selector to detect/manipulate the price value in pages that the price is not easily detected as some pages does not tag or id the elements

No file, test, or entry point is named in the issue. Start by locating the existing price and restock detection flow and its configuration or UI entry points, then determine how a user-supplied Regex, XPath, or CSS selector would be declared and verified; done means the configured selector reliably detects or manipulates the price value.

Written by the indexing model from the issue text.