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/diagnostics/tests/j+k/SupertypeArgumentsNullability-UserTypes.kt

@@ -15,7 +15,7 @@ public class Y extends X<A> {
 // FILE: test.kt
 
 fun main() {
-    Y().foo()<!UNSAFE_CALL!>.<!>hashCode()
+    Y().foo()<!UNSAFE_CALL!>.<!>wait()
     Y().bar(null)
 }