[Doc Feature] Format bot messages with enriched Markdown

[SirajShaik-MSFT]

ADO: https://domoreexp.visualstudio.com/MSTeams/_workitems/edit/5411954

Preview links:

• Customize bot messages
• Best practices for building agent in Teams user experience
• Stream bot messages

[learn-build-service-prod]

PoliCheck Scan Report

The following report lists PoliCheck issues in PR files. Before you merge the PR, you must fix all severity-1 and severity-2 issues. The AI Review Details column lists suggestions for either removing or replacing the terms. If you find a false positive result, mention it in a PR comment and include this text: #policheck-false-positive. This feedback helps reduce false positives in future scans.

✅ No issues found

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[learn-build-service-prod]

Learn Build status updates of commit 5405294:

✅ Validation status: passed

File	Status	Preview URL	Details
msteams-platform/bots/how-to/format-your-bot-messages.md	✅Succeeded	View
msteams-platform/bots/how-to/includes/streaming-with-extended-markdown.md	✅Succeeded	View
msteams-platform/bots/how-to/teams-conversational-ai/ai-ux.md	✅Succeeded	View
msteams-platform/bots/streaming-ux.md	✅Succeeded	View

For more details, please refer to the build report.