Refactored dark/light CSS + New Review Tab

[caronc]

Description:

Related issue (if applicable): refs #174

Added new Review Tab and moved content from what is loaded there.

Also, massive refactoring to CSS to just keep colors for dark theme and not maintain an entire copy of materialui and highlightjs with hacks put inside it.

E.g:

And Light Mode:

Checklist

• [x] The code change is tested and works locally.
• [x] There is no commented out code in this PR.
• [x] No lint errors (use flake8)
• [ ] Tests added