Allow AsyncSeq.mergeAll to accept seq instead of list

Widen the parameter type of AsyncSeq.mergeAll from 'AsyncSeq<'T> list'
to 'seq<AsyncSeq<'T>>'. This is backward-compatible since list implements
seq in F#, but also allows callers to pass arrays, other collections, or
lazy sequences without needing an explicit conversion.

The implementation materialises the seq to an array immediately since
random-access (indexed look-up) and Length are needed internally.

Closes #165

Co-authored-by: Copilot <[email protected]>

Author: github-actions[bot]

src/FSharp.Control.AsyncSeq/AsyncSeq.fs

@@ -1700,8 +1700,9 @@ module AsyncSeq =
 
   /// Merges all specified async sequences into an async sequence non-deterministically.
   // By moving the last emitted task to the end of the array, this algorithm achieves max-min fairness when merging AsyncSeqs
-  let mergeAll (ss:AsyncSeq<'T> list) : AsyncSeq<'T> =
+  let mergeAll (ss:seq<AsyncSeq<'T>>) : AsyncSeq<'T> =
     asyncSeq {
+      let ss = Seq.toArray ss
       let n = ss.Length
 
       let moveToEnd i (a: 'a[]) =

src/FSharp.Control.AsyncSeq/AsyncSeq.fsi

@@ -502,7 +502,7 @@ module AsyncSeq =
 
     /// Merges all specified async sequences into an async sequence non-deterministically.
     /// The resulting async sequence produces elements when any argument sequence produces an element.
-    val mergeAll : sources:AsyncSeq<'T> list -> AsyncSeq<'T>
+    val mergeAll : sources:seq<AsyncSeq<'T>> -> AsyncSeq<'T>
     #endif
 
     /// Returns an async sequence which contains no contiguous duplicate elements based on the specified comparison function.