add test to verify output files; correctly handle lambdas

idea/testData/coverage/outputFiles/lambda.expected.txt

@@ -0,0 +1,2 @@
+org/demo/coverage/Foo
+org/demo/coverage/Foo$bar$1

idea/testData/coverage/outputFiles/lambda.kt

@@ -0,0 +1,12 @@
+package org.demo.coverage
+
+public class Foo {
+    public fun forEach(fn: (Any?) -> Unit): Unit {
+    }
+
+    public fun bar() {
+        forEach {
+            println("foo")
+        }
+    }
+}