(feat) Comparing screenshots from the same test run

**Describe the solution you'd like** I am looking for a way to take screenshots of the app and compare them. The app I am testing uses HTML Canvas. I'm looking for a way to achieve this process: 1 - Take a screenshot, saved under a name 2 - Make a change to the UI 3 - Take a new screenshot 4 - Compare the first and second screenshots to see if the change actually happened. Looking at the docs, I couldn't see if this feature already exists. If it does, that would be great!