Force move async-closures that are FnOnce to make their inner coroutines also move

Author: compiler-errors

tests/pass/async-closure-captures.stderr

@@ -0,0 +1,14 @@
+Hello(0)
+Hello(0)
+Hello(1)
+Hello(1)
+Hello(2)
+Hello(3)
+Hello(3)
+Hello(4)
+Hello(4)
+Hello(5)
+Hello(6)
+Hello(7)
+Hello(8)
+Hello(9)