Docs: Add a contextual color mode switcher for each example

[louismaximepiton]

Description

⚠️ Merge after #39328.
⚠️ I tried to have at least the accessible behavior, but the rest might not be clean.
Add a color-mode switcher to every example.

Motivation & Context

Ease the color change checks for users.
Ease the reviews on our side.

Type of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Refactoring (non-breaking change)
• Breaking change (fix or feature that would change existing functionality)

Checklist

• I have read the contributing guidelines
• My code follows the code style of the project (using npm run lint)
• My change introduces changes to the documentation
• I have updated the documentation accordingly
• I have added tests to cover my changes
• All new and existing tests passed

Live previews

Every component/form will have this button added.

• https://deploy-preview-39274--twbs-bootstrap.netlify.app/docs/5.3/components/accordion

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