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/functions/genericOverriddenFunction.kt

@@ -0,0 +1,19 @@
+// TODO: muted automatically, investigate should it be ran for JS or not
+// IGNORE_BACKEND: JS
+
+// WITH_REFLECT
+
+import kotlin.test.assertEquals
+
+interface H<T> {
+    fun foo(): T?
+}
+
+interface A : H<A>
+
+fun box(): String {
+    assertEquals("A?", A::foo.returnType.toString())
+    assertEquals("T?", H<A>::foo.returnType.toString())
+
+    return "OK"
+}