The Witness: Add some unit tests

[NewSoupVi]

Idk if these make any sense but yeah

Also adds a hidden option allowing me (and people who know, I guess) to turn off the "put a random symbol on Tutorial Gate Open" thing

[NewSoupVi]

import worlds.terraria??? lol one sec, I'll fix that

[agilbert1412]

New tests == Good!

[Exempt-Medic]

Comments and questions were addressed, the tests pass and make sense for the game. The changes in __init__.py and options.py make sense as well

[black-sliver]

Collapse into one test :(

Why the sad face? :S
Besides the overhead of rolling games, I think it does make more sense to have all those checks "atomic" on a single game. (I don't expect the difference in performance to be too noticeable for most witness option combinations.)

In my mind the cut should happen where the code block stops making sense, becomes too large to follow easily or when you want a clean state/rely on modifying state (i.e. self.collect) unless it makes more sense to do atomically, i.e. soe/test/test_goal/test_fragments woiuld make no sense to run on multiple games and instead we "uncollect" Victory.