Add spec for Settings (#24879)

Summary:
part of #24875. I again, am not completely sure how the call site here works- appears settings can be directly accessed?

## Changelog

[General] [Added] - Add TM spec for Settings
Pull Request resolved: https://github.com/facebook/react-native/pull/24879

Reviewed By: RSNara

Differential Revision: D15543012

Pulled By: fkgozali

fbshipit-source-id: a1df3096a2fc5fe8e65d0ed2398912530bd3911a

Libraries/Settings/NativeSettingsManager.js

@@ -0,0 +1,24 @@
+/**
+ * Copyright (c) Facebook, Inc. and its affiliates.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ *
+ * @flow
+ * @format
+ */
+
+'use strict';
+
+import type {TurboModule} from 'RCTExport';
+import * as TurboModuleRegistry from 'TurboModuleRegistry';
+
+export interface Spec extends TurboModule {
+  +getConstants: () => {|
+    settings: Object,
+  |};
+  +setValues: (values: Object) => void;
+  +deleteValues: (values: Array<string>) => void;
+}
+
+export default TurboModuleRegistry.getEnforcing<Spec>('SettingsManager');

Libraries/Settings/Settings.ios.js

@@ -11,15 +11,15 @@
 'use strict';
 
 const RCTDeviceEventEmitter = require('../EventEmitter/RCTDeviceEventEmitter');
-const RCTSettingsManager = require('../BatchedBridge/NativeModules')
-  .SettingsManager;
+import NativeSettingsManager from './NativeSettingsManager';
 
 const invariant = require('invariant');
 
 const subscriptions: Array<{keys: Array<string>, callback: ?Function}> = [];
 
 const Settings = {
-  _settings: RCTSettingsManager && RCTSettingsManager.settings,
+  _settings:
+    NativeSettingsManager && NativeSettingsManager.getConstants().settings,
 
   get(key: string): mixed {
     return this._settings[key];
@@ -27,7 +27,7 @@ const Settings = {
 
   set(settings: Object) {
     this._settings = Object.assign(this._settings, settings);
-    RCTSettingsManager.setValues(settings);
+    NativeSettingsManager.setValues(settings);
   },
 
   watchKeys(keys: string | Array<string>, callback: Function): number {