Extract Function: Add test data

idea/testData/refactoring/extractFunction/controlFlow/unextractable/outputValueWithExpression.kt

@@ -0,0 +1,15 @@
+// NEXT_SIBLING:
+fun foo(a: Int): Int {
+    var b: Int = 1
+
+    val t = <selection>if (a > 0) {
+        b += a
+        b
+    }
+    else {
+        a
+    }</selection>
+    println(b)
+
+    return t
+}