Refactor stepping tests

idea/testData/debugger/tinyApp/src/stepping/stepIntoAndSmartStepInto/extFun.kt

@@ -0,0 +1,13 @@
+package extFun
+
+class A
+
+fun A.bar() {
+    val a = 1
+}
+
+fun main(args: Array<String>) {
+    val a = A()
+    //Breakpoint!
+    a.bar()
+}