Code themes and language support

[heckmon]

Description

Code support with custom themes

Why

The markdown_widget package supports code theming via the flutter_highlight package.
So it will be nice to add that feature to this package.

[gjwgit]

Thanks for the suggestion @heckmon. Happy to accept PRs. What is the use case for this though? Would you add highlighted code to a tooltip?

[heckmon]

@gjwgit , I have been creating a code_editor widget and it has the LSP hover feature. On hovering, it shows the markdown_widget as an overlay. So, if this widget had that features, I would have used this instead of markdown_widget.
This is the code editor package:

https://github.com/heckmon/code_forge

[gjwgit]

The code_forge work looks great. I understand the use case. I'll have to have a look how we might utilise flutter_highlight.