[Repo Assist] Add AsyncSeq.mapFold, mapFoldAsync, allPairs, rev#266

dsyme merged 4 commits intomainfsprojects/FSharp.Control.AsyncSeq:mainfrom

repo-assist/improve-new-combinators-87b33ebcb712bf81fsprojects/FSharp.Control.AsyncSeq:repo-assist/improve-new-combinators-87b33ebcb712bf81Copy head branch name to clipboard