Adding a new set + lookup is now atomic
Returns a readonly set, caller shouldn't be able to ever modify this data
Removed memory allocation when calling `GetRequiredOffersById` with a tpl that doesn't have any offerIds
Made `RagfairRequiredItemService` a singleton
Made `RagfairRequiredItemService ` store offerIds instead of offer objects, reducing memory footprint
Reworked `GetOffersThatRequireItem` to work with `RagfairRequiredItemService` changes
Moved `GenerateDynamicOffers` to run after garbage colelction, this means GC will work on memory prior to new offers being added but after stale offers are removed
Made `PaymentHelper` a singleton + Store currency tpls in a hashset instead of list
Comment improvements