Scoru: reward the winner during a refutation game

Context

Closes #3648 (closed)

Highly similar to the TORU's mechanism.

Manually testing the MR

Added a fancy tezt test which check every balances, every time. Might be too much, might me enough, might be perfect.

Checklist

• n/a Document the interface of any function added or modified (see the coding guidelines)
• n/a Document any change to the user interface, including configuration parameters (see node configuration)
• Provide automatic testing (see the testing guide).
• n/a For new features and bug fixes, add an item in the appropriate changelog (docs/protocols/alpha.rst for the protocol and the environment, CHANGES.rst at the root of the repository for everything else).
• Select suitable reviewers using the Reviewers field below.
• Select as Assignee the next person who should take action on that MR