Add dark theme for all editors and more syntax highlighting for text editors

[Narnillian]

The editory doesn't look as good as other editors. I understand that there's High Contrast Mode, but that is also hard on eyes.

Please make a Dark Theme for all editors. Also, please add more syntax highlighting. Variables are not highlighted right now, and it would be so much nicer looking and easier if they were. As well, some built-in functions are highlighted, and some are not. No in-code functions are highlighted.

I am using Python, in ChromeOS 99.0.4844.86