Re-land "[RN] TM: attempt to integrate with internal codegen infra""

Summary: This is a re-land of https://github.com/facebook/react-native/commit/66e02588850ee81aa8574edc46c954e7bccf42e7 after fixing internal build failures.

Reviewed By: mdvacca

Differential Revision: D15764832

fbshipit-source-id: f4fb347a9c6c02fb146b24ba395436bd31a37deb

Libraries/Alert/Alert.js

@@ -15,7 +15,23 @@ import NativeDialogManagerAndroid, {
   type DialogOptions,
 } from '../NativeModules/specs/NativeDialogManagerAndroid';
 import RCTAlertManager from './RCTAlertManager';
-import {type Buttons, type Options, type AlertType} from './NativeAlertManager';
+
+export type AlertType =
+  | 'default'
+  | 'plain-text'
+  | 'secure-text'
+  | 'login-password';
+export type AlertButtonStyle = 'default' | 'cancel' | 'destructive';
+export type Buttons = Array<{
+  text?: string,
+  onPress?: ?Function,
+  style?: AlertButtonStyle,
+}>;
+
+type Options = {
+  cancelable?: ?boolean,
+  onDismiss?: ?() => void,
+};
 
 /**
  * Launches an alert dialog with the specified title and message.

Libraries/Alert/NativeAlertManager.js

@@ -13,27 +13,10 @@
 import type {TurboModule} from '../TurboModule/RCTExport';
 import * as TurboModuleRegistry from '../TurboModule/TurboModuleRegistry';
 
-export type Buttons = Array<{
-  text?: string,
-  onPress?: ?Function,
-  style?: AlertButtonStyle,
-}>;
-
-export type Options = {
-  cancelable?: ?boolean,
-  onDismiss?: ?() => void,
-};
-
-/* 'default' | plain-text' | 'secure-text' | 'login-password' */
-export type AlertType = string;
-
-/* 'default' | 'cancel' | 'destructive' */
-export type AlertButtonStyle = string;
-
 export type Args = {|
   title?: string,
   message?: string,
-  buttons?: Buttons,
+  buttons?: Object, // TODO: have a better type
   type?: string,
   defaultValue?: string,
   cancelButtonKey?: string,

Libraries/ReactNative/NativeUIManager.js

@@ -30,7 +30,7 @@ export interface Spec extends TurboModule {
   +blur: (reactTag: ?number) => void;
   +findSubviewIn: (
     reactTag: ?number,
-    point: [number, number],
+    point: Array<number>,
     callback: (
       nativeViewTag: number,
       left: number,