ci: Added visual tests

[bentleyvk]

• I tried to use cypress components tests but I couldn't make them work because:
  • At first I had problems with esbuild since it has different binaries for different OS but I found workaround to run npm rebuild esbuild in Docker container.
  • Then I encountered issue related to monorepo as inside packages are symlinked and Windows links doesn't work in Linux container. If I relinked manually in container, then build won't work in Windows. Dockerfile ADD command does not follow symlinks on host moby/moby#1676
• I wanted to make that dev server is running on host and Docker container runs tests on it. It worked on my machine but it didn't work on CI. I tried different Docker arguments and other hacks but just running built demo page inside container seemed to be simpler solution.
• There are several different cypress visual testing plugins but cypress-image-diff-js has better API, report showing and more recent updates when others' last release date is 1-2 years ago.
• I decided to use 4K, Full HD, 1366x768 (20% of desktop users screen resolution), Tablet and Mobile breakpoints for testing.
• I added react-router-dom for better navigation.
• I added CONTRIBUTING.md with some explanations but it is still WIP.

Closes #7

[FlyersPh9]

I don't know if this is something I can review.

[gretanausedaite]

🌤️