Enable dark mode for storybook UI

[rajsite]

Pull Request

🤨 Rationale

For the Storybook UI the PR follows the configured system theme to enable light or dark mode for the manager ui and the docs ui

👩‍💻 Implementation

• Add a dark theme to the storybook theme
• Use storybook's getPreferredColorScheme similar to how the storybook normal theme is implemented
• Avoided changing the default selected theme for the canvas to the system theme as that had funny behavior. It stays defaulted to light theme.

🧪 Testing

Tried storybook locally and rely on no Chromatic diffs.

✅ Checklist

• I have updated the project documentation to reflect my changes or determined no changes are needed.

[rajsite]

@fredvisser if you wanna give a quick review of the chosen values (I just eye-balled it). These impact the manager, addons, and docs parts of the ui but not the canvas renders. I'll make updates to the constants but it's night and weekends so any other changes will be follow-on.

[rajsite]

@jattasNI @fredvisser bypass merging as it's not source changes and can handle feedback in nights-and-weekends as follow-on