[Repo Assist] Add AsyncSeq.sumBy, sumByAsync, average, averageBy, averageByAsync#245

dsyme merged 2 commits intomainfsprojects/FSharp.Control.AsyncSeq:mainfrom

repo-assist/improve-sumby-average-20260223-705926e5f065fa3afsprojects/FSharp.Control.AsyncSeq:repo-assist/improve-sumby-average-20260223-705926e5f065fa3aCopy head branch name to clipboard