Expand workshop to be more guided

[nuke-web3]

I suggest we include a few todo!() blocks for people to implement in the workshop, with the instructor doing one or two of them, and encouraging the students to then make their own beyond the provided ones.

The ultimate end point if people wanted to achieve it from this base code: a Kani wrapper for SCALE for a full code coverage verification suite of the SCALE repo for it's public API 🤔 WDYT?