support mermaid.js

[individual-it]

Description

Allow presentations to contain mermaid flowcharts

Motivation and Context

have fun

How Has This Been Tested?

• running locally with the example file

Screenshots (if appropriate):

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)
• Tests only (no source changes)
• Documentation only (no source changes)
• Maintenance (e.g. dependency updates or tooling)

Checklist:

• Code changes
• Unit tests added
• Acceptance tests added
• Documentation updated

[saw-jan]

🚀