[FEATURE] - Mermaid Diagrams

[Dragonsong3k]

It would be great to get syntax highlighting for code blocks in the PREVIEW pane.
Also, adding support to render mermaid diagrams.

[mariinkys]

Syntax highlighting should work in the preview pane so that's a bug, mermaid graphics support is something I have in mind but I'm still thinking about the implementation.

[mariinkys]

The syntax highlighting issue doesn't happen if instead of csharp you use cs as a language tag, I don't know right now why it works as csharp in the Editor tab and not in the preview tab tho.