[JVM] Improve debug step behavior around lambdas.

- Add tests to clarify problematic behavior
- Avoid line numbers on return instructions of lambdas without explicit returns

compiler/testData/debug/stepping/voidLambdaStepInline.kt

@@ -0,0 +1,16 @@
+
+// FILE: test.kt
+fun box(): String {
+    run { "O" + "K" }
+    run {
+        "O" + "K"
+    }
+    return "OK"
+}
+
+// LINENUMBERS
+// test.kt:4
+// test.kt:5
+// test.kt:6
+// test.kt:5
+// test.kt:8