Rename Stream<T> to Sequence<T> and provide migration path via deprecated types and functions.

libraries/stdlib/test/iterators/FunctionIteratorTest.kt

@@ -10,7 +10,7 @@ class FunctionIteratorTest {
     Test fun iterateOverFunction() {
         var count = 3
 
-        val iter = stream<Int> {
+        val iter = sequence<Int> {
             count--
             if (count >= 0) count else null
         }
@@ -20,7 +20,7 @@ class FunctionIteratorTest {
     }
 
     Test fun iterateOverFunction2() {
-        val values = stream<Int>(3) { n -> if (n > 0) n - 1 else null }
+        val values = sequence<Int>(3) { n -> if (n > 0) n - 1 else null }
         assertEquals(arrayListOf(3, 2, 1, 0), values.toList())
     }
 }