[Feature]: Team preview for optimal balance games

### Describe the Feature

Optimal balance games have only one outcome (compared to flexible balance), so there should be a team preview so that imbalance can be seen and manually corrected. Imbalanced games can happen with optimal balance when there is very high rating disparity since depending on the map, rating can have a disproportionate effect on the game's outcome (for example 2 2k rated players + 2 1ks vs a team of 4 1.5ks).

### Expected Behavior

When the game fills (to avoid excessive UI movement), the slots are sorted into optimal teams by rating. Players shouldn't be un-readied due to the slot change.

### Screenshots

_No response_

### Additional context

We do have a button to autobalance teams by slot (penguin autobalance), but it causes everyone to un-ready, which slows down how fast the game starts.