Migrate nonlocal games: GHZ game classical

[ggridin]

The link to the issue: #1596

This pull request is covering

1. GHZ classic tasks 1.1
2. GHZ task 1.2 (random) is dropped. Task 1.3 is expanded into implementation of 3 strategies (Alice, Bob and Charlie)
   This approach allow to create more complicated output like [true, false, false] or [r, DrawRandomBool(0.8), not t]
3. GHZ classic task 1.4

[ggridin]

Questions for this PR:

1. The mentioned winning strategies in solution.md are [true, true, true] and [true, false, false]
   There are also [true, true, z], [false, y, z] and more. Should we ask student an optional question to find more winning strategies?

Testing done:

Build "python ./build.py" is successful
Placeholder cases are syntactically correct but failing verifications.
Solutions are successful.
Some other failure scenarios were tested manually:
Exercise "Classical Strategy":

• [true, true, true]
• [true, false, false]
• [true, true, z]
• [false, y, z]
  and combinations of them. Negative scenarios were tested also.
  Exercise "GHZ Classical Game":
• return [a, b, c]
• return [true, true, true] (without use of strategies)
• return [a, b, true]
• return [a, c, b]
  and combinations of them. Negative scenarios were tested also.

[tcNickolas]

Looks good! I like the tweak on the second task to allow everybody to use a different classical strategy, since we can do it easily with the new infrastructure!

I left some cosmetic comments, nothing major.

Thank you!

[tcNickolas]

Looks great! (Apologies for the delay reviewing, trying to wrap as many things up as I can before disappearing until next week...)

Thank you!!

[ScottCarda-MS]

This looks great! Thanks for putting the time in to get this done!