Allows overwriting the sample downloaded by the contestant to make it different from the one used during testing

[cubercsl]

Description of the enhancement request

The samples shown in the problem statement may differ from those used by the judge.

In some problems, the samples shown in the PDF are NOT actually the test cases used by the judge.

For examples:

1. The sample output only shows the output format and is not the correct answer.
2. There are multiple valid outputs, the examples show a trivial one. The answer of other test cases may be generated by the main correct solution.
3. Interactive problem.

This is specified in Kattis/problem-package-format#291.

• For 1, this is impossible for now, unless making some special handling on the output validator， but I think this is not a good approach.
• For 2, we can temporarily do this by manually editing the sample output in the UI or problem package.
• For 3, we generally do not provide sample downloads but provide attachments instead.

The goal you want to achieve

It is hoped that the samples downloaded by the contestants can be overwritten according to the data/sample/statement or data/sample/download directories mentioned in the latest draft problem package format to support some scenarios.