CI to simulate applications

[JuanSapriza]

We would like a CI that actually simulates applications, not only compiles them.

This presents several challenges:

• Install Verilator on the container.
• Eventually, if the size of the container grows too much, host the runner ourselves.
• Modify all apps to make sure they all return at some point, and return a certain value.
• Warn that running on Verilator does not guarantee working for other configurations.