Delete Hashable, pull up its members to Any

Extensions on nullable types remain in Library.kt

 #KT-1741 Obsolete
 #KT-2805 Obsolete
 #KT-1365 Fixed
 #KT-4517 In Progress

compiler/testData/codegen/boxWithStdlib/dataClasses/hashcode/alreadyDeclared.kt

@@ -1,5 +1,5 @@
 data class A(val x: Int) {
-  fun hashCode(): Int = -3
+  override fun hashCode(): Int = -3
 }
 
 fun box(): String {