Add POC for new integrated math nodes

[thecodrr]

The previous math nodes (inline and block) are designed in an awkward manner causing various issues with selection etc. This POC is an attempt to integrate these nodes just like code blocks.

What's improved:

1. Syntax highlighting for LaTeX (and linting if possible)
2. Improved responsiveness when moving into or out of a math node
3. More control over UI and styling
4. Easier to theme
5. Live rendering for Math

What needs to be worked on:

• Math block and code block are currently duplicating a lot of code. It'd be great if we can somehow refactor these 2 extensions to share the code where possible.
• Add live rendering updates as the user makes edits
• Remove old math plugins
• Fix code block glitches with selection and text entry.