[Test] Move KotlinAgainstKotlin tests under BlackBoxCodegen tests

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

@@ -0,0 +1,16 @@
+// MODULE: lib
+// FILE: A.kt
+
+class A(vararg s: String) {
+
+}
+
+// MODULE: main(lib)
+// FILE: B.kt
+
+fun box(): String {
+    A()
+    A("a")
+    A("a", "b")
+    return "OK"
+}