[MarkdownSection] Adds code highlighting

[oneolddev]

Pull Request

📖 Description

Adds code highlighting for code blocks in markdown file consistent with CodeSnippet component.

• A Markdig extension was added to replace the default one provided by Markdig to add classes to the generated HTML pre tags.
• Javascript was added to call the hljs.highlightElement for each code block.
• Copy button was added.

🎫 Issues

An example of use with the DesignTokens page

Current appearance

New appearance

👩‍💻 Reviewer Notes

This is the first Markdig extension I have written. I opted to clone the original CodeBlockRenderer and only modify.

📑 Test Plan

Tested with demo site - Client and Server

✅ 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 compontent
• I have modified an existing component
• I have validate Unit Tests for an existing component

⏭ Next Steps