[MenuButton] Add an optional start icon

[adtaylor-cs]

Pull Request

📖 Description

This is a small PR to add the ability to add an icon to the start of a FluentMenuButton.

🎫 Issues

N/A

👩‍💻 Reviewer Notes

This is a pretty small change, and I've added an example to the Demo site. The result is as seen in this screenshot:

📑 Test Plan

Added to the existing FluentMenuButton unit test.

✅ Checklist

General

• I have added tests for my changes.
• I have tested my changes.
• I have updated the project documentation to reflect my changes.
• I have read the CONTRIBUTING documentation and followed the standards for this project.

Component-specific

• I have added a new component
• I have added Unit Tests for my new component
• I have modified an existing component
• I have validated the Unit Tests for an existing component

⏭ Next Steps

N/A

Resolved