Add a "Breaking down a project into tickets (and unblock each other)" workshop to ITP

[illicitonion]

In the Piscine we currently give groups projects to do without breaking them down into tickets.

For the first couple of Piscines we've had to give an ad-hoc workshop on how to do this, because ITP doesn't currently teach these skills.

We should introduce a workshop in ITP (probably in Data Flows) to introduce this.

We have a similar workshop in the SDC (https://sdc.codeyourfuture.io/decomposition/sprints/1/day-plan/#breaking-down-features-workshop) but it's focused on a specific project and is specifically talking about backends and frontends, which is a bit too much for ITP. We probably want to use "if we can agree on the keys in an object" or "if we can agree how to serialise to localStorage and then how to deserialise" or something as our example.