Move some tests from boxWithStdlib/ to box/

Move those tests which do not require neither stdlib nor reflect

compiler/testData/codegen/box/dataClasses/equals/sameinstance.kt

@@ -0,0 +1,7 @@
+data class A(val arg: Any? = null)
+
+fun box() : String {
+  val a = A()
+  val b = a
+  return if(b == a) "OK" else "fail"
+}