I14 implement ast visualisation

[krrome]

Teal PR Checklist

Thanks so much for your PR!

Before hitting Create, please check you've covered these points - it'll make the
process much smoother :).

Have you...

• Run the tests (make test, or pytest --runslow --testddb)
• Checked for lint errors (make lint, or use the command in Makefile)
• Run the example projects
• Updated CHANGELOG.md
• Updated the Teal Guide (optional)

If not, why not?

Explanation

(Feel free to delete this section - it's just a quick explanation of the
motivation behind the checklist).

Run the example projects

Take 5 minutes to clone and run the example projects from start to finish, as no
integration test really covers everything!

Update CHANGELOG.md

Any notable changes should be documented in the CHANGELOG. Friends don't make
friends read git commit logs.

Add a brief description of your change to the "unreleased" section.

Update the Teal Guide

If your change is anything other than fixing a bug, please update the Teal Guide
so that people know about your change.

open todos:

• collapse leaf nodes into Argument nodes, binary exprs
• remove imports
• highlight trigger functions + integrate info from toml
• highlight python calls
• all lists are single Nodes except