Goal condition check refactoring and tests for all existing conditions

[Budderfriend]

Description

The IsPuzzleComplete() function in the Puzzle class has been rewritten alongside several helper functions in order to make the code more readable as well as make it much easier to add new goal conditions in the future. Tests have been written for all existing goal conditions.

Type of change

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Enhancement (improvement to an already existing feature)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)

Checklist:

• I have performed a self-review of my code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation (if applicable)
• My changes generate no new warnings
• I have added tests that prove my fix is effective or that my feature works
• New and existing unit tests pass locally with my changes