Implement replacement bbcode parser for authoring lesson content

[Razoric480]

This is a work in progress to implement #1188

Making some edits to the existing lessons again it was pretty slow. The point of this is to have an upgrade path to a new format that will replace the Godot resources, get rid of the editor plugin for authoring, and improve iteration speed when working on the content.

We can still have editor tools later on but now it would become a simpler list of lessons and code editor with syntax highlighting for BBCode tags instead of a more complex interface with blocks we drag and drop.

Supercedes #1191

Current changes

• Rebased branch off of latest main
• Patched current implementation so that the app is functional and can be run through from start to finish
  • The app would depend on the resource_path being set, but godot will not set resource_path if it's already taken, requiring take_over_path. Likewise, practices would use resource_path for comparison but those didn't get set on the BBCode ones, so now it uses the practice_id to find the appropriate ID
• Fixed bbcode with missing tags (description and starting code are not optional) which would result in some blank lessons as they error'ed out
• Added bbcode files to export presets so they can be exported with the app along with the lgd files
• Added a CourseIndex base script to define course lesson paths
• Deleted old course and lesson TRES since they are created from BBCode

Upcoming TODO

• Start working on the angle of attack to remove the need for intermediate resource files