Facade gives a simple, single entry point in front of a complex
subsystem, so callers don't need to know how the pieces fit together.
CPU, Memory and HardDrive each expose low-level operations.
Implement ComputerFacade.start() to sequence the correct boot steps and
return them, in order, as a list.
solve(n) calls start() n times and returns each resulting sequence
(verifying the facade is deterministic and repeatable).
Sample tests