Delete kotlin.jvm.internal.KObject

It was supposed to be used in reflection but the benefits do not outweigh the
cost of KT-6951

 #KT-3223 Fixed
 #KT-6951 Fixed

compiler/testData/classpathOrder/kotlin/jvm/internal/Ref.java

@@ -0,0 +1,7 @@
+package kotlin.jvm.internal;
+
+public class Ref {
+    public static String methodWhichDoesNotExistInKotlinRuntime() {
+        return ":)";
+    }
+}