Code a program to convert course content to the new platform

[NathanLovato]

1. Convert relative image paths to absolute paths.

/courses/$COURSE_FOLDER/$CHAPTER_SLUG/images/$IMAGE_NAME

2. Add Yaml frontmatter at the top of lessons like this:

---
title: Importing the project and placing the player character
slug: importing-the-project-and-placing-the-player-character
draft: false
free: false
---

3. Add _index.md files inside of the chapter folders with front matter:

---
title: Assembling game
slug: assembling-game
---

4. Extract nim course builder features

Add SVG icons without the {=html} mark Process include shortcodes

5. Replace links with absolute links

E.g.

{{ link learn-to-code-how-to-install-godot How to download and run Godot }} -> How to download and run Godot

6. Remove HTML comments

[NathanLovato]

There's a temporary python script in the repo to get the project going, but the idea's to make a self-contained executable with Nim.

See programs/convert_course_content_to_new_platform.py