Use source map to improve the Hedy debugger

[Felienne]

We currently have a basic debugger (see #2704 and the associated PRs) that works by transpiling 1 line and then the next line etc.

That works relatively well, but of course it breaks when we come to level 7 and there are loops. We then needs something really extensive like a source map that actually keep track of what line of Hedy generate what line of Python and then just executes those. It will also require soms more front-end tweaking to execute a partial program but of course it will be SUPER valuable to have this feature for higher levels too!

[Felienne]

Moving this to Current Student Projects because @jpelay will pick it up!

[Felienne]

Almost ready, so this can be archived!!