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/alreadyDeclared.kt

@@ -1,5 +1,5 @@
 data class A(val x: Int) {
-  fun equals(other: Any?): Boolean = false
+  override fun equals(other: Any?): Boolean = false
 }
 
 fun box(): String {

compiler/testData/codegen/boxWithStdlib/dataClasses/equals/alreadyDeclaredWrongSignature.kt

@@ -16,7 +16,7 @@ data class D(val x: Int) {
 
 data class E(val x: Int) {
   fun equals(x: E): Boolean = false
-  fun equals(x: Any?): Boolean = false
+  override fun equals(x: Any?): Boolean = false
 }
 
 fun box(): String {

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)

compiler/testData/codegen/boxWithStdlib/dataClasses/equals/nullother.kt

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

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 {