Negative Event: Player should recieve slowness debuff when an exam is completed incorrectly. #8

Following from #4, one of our new negative events will make the player receive a debuff to slow down the player movement temporarily, if they get the question on the exam dialog wrong.

Checklist items for slowness debuff:

• Implement question dialog when an exam is complete.
• Create a new interface for player effects (immunity, hurt, slowed down/speed boosted e.t.c.)
• Create a new class for applying slowness debuff.
  • Put debuff on a 10 second timer.
  • Only apply effect once the question in the exam dialog is wrong.
• Add unit tests for slowness debuff class.