Refactoring + minor fixes: destructure intention

idea/testData/intentions/iterationOverMap/OnlyKeyUsed.kt.after

@@ -0,0 +1,10 @@
+// WITH_RUNTIME
+
+fun main(args: Array<String>) {
+    val map = hashMapOf(1 to 1)
+    for ((key) in map) {
+        val key2 = key
+
+        println(key)
+    }
+}