getRandomWeightedReward now takes any object with lowercase 'rarity', and the only alternative to it is the 'uc' variant which takes any object with uppercase 'Rarity'
usage of IRngResult is now also optional
Reviewed-on: OpenWF/SpaceNinjaServer#1073
Co-authored-by: Sainan <sainan@calamity.inc>
Co-committed-by: Sainan <sainan@calamity.inc>