Cherrypick of #58457 in master
Caused by reusing icons from the main editor in the code editor. These
icons were converted based on the main editor theme and not the code
editor theme.
- Create new icons for use specifically in the code editor
- Add these icons to the exceptions when converting dark theme icons
to light theme automatically
- Change the default value of the code folding color to match previous
color
- Code folding icon is now pure white by default to correctly match
the color defined in settings
