backend/tests: Add blackbox tests from Kotlin JVM

Added tests from testData/codegen/box directory. There are blackbox tests
in other directories and they are to be added.

backend.native/tests/external/codegen/blackbox/reflection/enclosing/lambdaInFunction.kt

@@ -0,0 +1,20 @@
+// TODO: muted automatically, investigate should it be ran for JS or not
+// IGNORE_BACKEND: JS
+
+// WITH_REFLECT
+
+fun box(): String {
+    val l: Any = {}
+
+    val javaClass = l.javaClass
+    val enclosingMethod = javaClass.getEnclosingMethod()
+    if (enclosingMethod?.getName() != "box") return "method: $enclosingMethod"
+
+    val enclosingClass = javaClass.getEnclosingClass()!!.getName()
+    if (enclosingClass != "LambdaInFunctionKt") return "enclosing class: $enclosingClass"
+
+    val declaringClass = javaClass.getDeclaringClass()
+    if (declaringClass != null) return "anonymous function has a declaring class: $declaringClass"
+
+    return "OK"
+}