Resolve "Script trains"

Closes #72 (closed) #91 (closed)

What does this MR do (summary)?

• Adds script train functionality back
• Adds an API for scripts to check submissions
• Makes feedback only visible to the appropriate roles

Does this MR meet the acceptance criteria?

• The main application was run to make sure the server still runs without errors.
• Tests were written to verify the behaviour of this code.
• Javadoc and other comments were added to make the code understandable.
• The code adheres to the style guidelines.