Update border and background color tokens

[thatblindgeye]

For the chatbot, header, content, and footer containers, background color should be using a floating secondary token for docked and overlay displays.

For the MessageBar, the border color and background should be using a control default.

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Jira Issue: PF-4219

[github-actions]

🎉 This issue has been resolved in version 6.6.0-prerelease.7 🎉

The release is available on:

• GitHub release
• npm package (@prerelease dist-tag)

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