fix(Objects 1 Answer placeholders): Split answer placeholders

[sofiiako]

The description mentions: "The starter code in main() will show you how to write these." but there was no main() in the starter code, only a package name, import statement, and a //todo. Changed placeholders to keep necessary parts in the starter code

Closes https://youtrack.jetbrains.com/issue/EDC-472

[svtk]

Commenting the code in the solution doesn't work: then we stop checking automatically that the solution is correct. What I have to do is to insert the same commented code in the placeholder text, and leave it uncommented in the solution.