[Test] Move KotlinAgainstKotlin tests under BlackBoxCodegen tests

compiler/testData/codegen/box/compileKotlinAgainstKotlin/delegatedDefault.kt

@@ -0,0 +1,19 @@
+// MODULE: lib
+// FILE: A.kt
+package lib
+
+interface A {
+    fun f(x: String = "OK"): String
+}
+
+class B : A {
+    override fun f(x: String) = x
+}
+
+class C(val x: A) : A by x
+
+// MODULE: main(lib)
+// FILE: B.kt
+import lib.*
+
+fun box() = C(B()).f()