Feature Request: Syntax Highlighting Widget

[codename-irvin]

It would be great if we could add a syntax highlighting widget to Walnut. From my research, it doesn't appear that there is an out-of-the-box solution for this in ImGui. Perhaps we could create such a widget here and then attempt to have it added to ImGui once it is feature-complete and stable.

As far as implementation goes, I think we have a couple of options:

1. Create the widget from scratch including lexing for popular languages
2. Create a Scintilla port for ImGui + Vulkan

There is one repo I found that implements syntax highlighting for ImGui. However, it seems to be out of active development and only supports a few languages.

Anyways, I thought I would just kick off a conversation to see if there is interest in adding something like this into Walnut and to gather suggestions for the best approach.