Restore and undeprecate removed Iterator.forEach().

libraries/stdlib/src/kotlin/collections/Iterators.kt

@@ -16,6 +16,13 @@ public fun <T> Enumeration<T>.iterator(): Iterator<T> = object : Iterator<T> {
  */
 public fun <T> Iterator<T>.iterator(): Iterator<T> = this
 
+/**
+ * Performs the given [operation] on each element of this [Iterator].
+ */
+public inline fun <T> Iterator<T>.forEach(operation: (T) -> Unit) : Unit {
+    for (element in this) operation(element)
+}
+
 /**
  * Data class representing a value from a collection or sequence, along with its index in that collection or sequence.
  *