Boosters are sorted by rarity even when generated by collation

Example: Modern Masters (MMA) has a dedicated foil slot that is found after the rare at the end of the booster. The collator appears to add it last. However, it seems that it appears after the other cards of its rarity in the booster instead.

I'm not sure what part of the code is sorting the booster by rarity, but such functionality is NOT desired for boosters generated by collation with dedicated slots: they should be presented as generated.

Start by tracing booster generation and collation order for Modern Masters, then locate where generated cards are sorted by rarity. Reproduce the dedicated foil-slot case and verify that boosters produced by collation preserve their generated order rather than being reordered by rarity.

Written by the indexing model from the issue text.