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/equals/instanceof.kt

@@ -1,5 +1,5 @@
 class Dummy {
-  fun equals(other: Any?) = true
+  override fun equals(other: Any?) = true
 }
 
 open data class A(val v: Any)