Visual Review Tool screenshot research spike

We need to handle a large research spike for how to handle screenshots for our "Visual Review Tool" on review apps.

Based on this thread: https://gitlab.com/gitlab-org/gitlab-ee/issues/10765#note_176768875.

We will need to research possible solutions for this feature, primarily in how the screenshot is going to be taken. A proof-of-concept would be great to have, as well as an official proposal explaining the research done and why the chosen solution is best. It would be best to keep this research spike as an ongoing discussion throughout the month, instead of only a final presentation.

Some current discussions/links:

• html2canvas NPM library that takes a DOM screenshot.
  • However, it states in the documentation "The screenshot is based on the DOM and as such may not be 100% accurate to the real representation as it does not make an actual screenshot, but builds the screenshot based on the information available on the page." So this may not be the best solution.
• This tutorial on how to use html2canvas in Vue.
• There are other products that implement this feature, so we can research how they are handling it.