Removed ability to change TreeTent goals

[Kevin-771]

Description

Fixed a bug where when solving a TreeTent puzzle, we were able to change the goals of the puzzle

Closes #623

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)

How Has This Been Tested?

After the change, I opened a few TreeTent puzzles and I was not able to edit the puzzle goals.

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

[Corppet]

Make sure you are working in the origin/dev branch. origin/master is reserved for releases and should not be directly worked on/merged. There are also a lot of changes in dev that may not currently be present in master, so your changes may create conflicts with updated files or has already been addressed (which I believe in this case has not).