docs: add javadoc to classes without doc

...ava/edu/ntnu/idatt2001/group_30/paths/PathsSingleton.java

.../ntnu/idatt2001/group_30/paths/controller/Controller.java

...001/group_30/paths/controller/CreatePlayerController.java

...u/idatt2001/group_30/paths/controller/HelpController.java

...datt2001/group_30/paths/controller/NewGameController.java

...att2001/group_30/paths/controller/NewStoryController.java

...in/java/edu/ntnu/idatt2001/group_30/paths/model/Game.java

...nu/idatt2001/group_30/paths/model/actions/GoldAction.java

.../idatt2001/group_30/paths/model/actions/HealthAction.java

...att2001/group_30/paths/model/actions/InventoryAction.java

...u/idatt2001/group_30/paths/model/actions/ScoreAction.java

...tnu/idatt2001/group_30/paths/model/goals/GoalFactory.java

...u/ntnu/idatt2001/group_30/paths/model/goals/GoalType.java

...u/ntnu/idatt2001/group_30/paths/model/goals/GoldGoal.java

.../ntnu/idatt2001/group_30/paths/model/goals/ScoreGoal.java

.../idatt2001/group_30/paths/model/utils/TextValidation.java

...datt2001/group_30/paths/view/components/CreatePlayer.java

...att2001/group_30/paths/view/components/ImageCarousel.java

.../group_30/paths/view/components/pop_up/AbstractPopUp.java

...001/group_30/paths/view/components/pop_up/GoalsPopUp.java