[Test] Move KotlinAgainstKotlin tests under BlackBoxCodegen tests

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

@@ -0,0 +1,19 @@
+// MODULE: lib
+// FILE: A.kt
+
+package aaa
+
+enum class E {
+    TRIVIAL_ENTRY,
+    SUBCLASS { }
+}
+
+// MODULE: main(lib)
+// FILE: B.kt
+
+import aaa.E
+
+fun box(): String {
+    if (E.TRIVIAL_ENTRY == E.SUBCLASS) return "Fail"
+    return "OK"
+}