Make rated games more strict

From discord -- rated games must be more strict:
* no free mulligans;
* no 1 game wins;
* no AI;
* no password protected;
* TODO: other limitations?

After #5525 completed (save/load match configs) it's possible to make strict game types with standard server side configs. And that's games can be rates.

Review the saved match configuration work in #5525 first, then trace how standard server-side game configurations define rated games. Clarify the complete set of restrictions, including mulligans, one-game wins, AI participation, and password protection. Done means rated games consistently enforce the agreed limitations.

Written by the indexing model from the issue text.