Feature course progress tracker

[StianSto]

added a progress tracker. tracks the whole course by default, but can track specific modules as well

summary:

• an entity is completed when the user scrolls to the bottom of a page
• on completion:
  • it checks if entity has any children and if so all children must already be completed
  • recursively checks parents upward. it achives this by utilising a map in svelte store. i guess it could classify as a hashmap?
• all data is stored in localstorage and is update on change by svelte