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/enum/enumInheritedFromTrait.kt

@@ -0,0 +1,16 @@
+package test
+
+fun box() = MyEnum.E1.f() + MyEnum.E2.f()
+
+enum class MyEnum : T {
+    E1 {
+        override fun f() = "O"
+    },
+    E2 {
+        override fun f() = "K"
+    }
+}
+
+interface T {
+    fun f(): String
+}