add hashUnordered that uses a walk method and hashes all elements

crates/compiler/builtins/roc/Hash.roc

@@ -81,3 +81,23 @@ hashStrBytes = \hasher, s ->
 hashList = \hasher, lst ->
     List.walk lst hasher \accumHasher, elem ->
         hash accumHasher elem
+
+hashUnordered = \hasher, container, walk ->
+    walk
+        container
+        0
+        (\accum, elem ->
+            x =
+                hasher
+                |> new
+                |> hash elem
+                |> complete
+            nextAccum = Num.addWrap accum x
+
+            if nextAccum < accum then
+                # we dont want to lose a bit of entropy on overflow, so add it back in.
+                Num.addWrap nextAccum 1
+            else
+                nextAccum
+        )
+    |> \accum -> addU64 hasher accum