Allow applicationId to be specified on build

Summary:
Added the ability to define a specific applicationId (in case it's different to the package name)

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We have a specific requirement that our package name differs from the applicationId but not in a way that allows us to add it as a suffix to our package name. I wanted to add the option to specify a specific applicationId.

`react-native run-android --appId <Specific Application Id>`
Closes facebook#14524

Differential Revision: D5910259

Pulled By: shergin

fbshipit-source-id: 768fbc910f6b520dd18936f6bceeee136fca7025

Author: shockdesign

local-cli/runAndroid/runAndroid.js

@@ -88,6 +88,16 @@ function tryRunAdbReverse(packagerPort, device) {
   }
 }
 
+function getPackageNameWithSuffix(appId, appIdSuffix, packageName) {
+  if (appId) {
+    return appId;
+  } else if (appIdSuffix) {
+    return packageName + '.' + appIdSuffix;
+  }
+
+  return packageName;
+}
+
 // Builds the app and runs it on a connected emulator / device.
 function buildAndRun(args) {
   process.chdir(path.join(args.root, 'android'));
@@ -100,7 +110,7 @@ function buildAndRun(args) {
       'utf8'
     ).match(/package="(.+?)"/)[1];
 
-  const packageNameWithSuffix = args.appIdSuffix ? packageName + '.' + args.appIdSuffix : packageName;
+  const packageNameWithSuffix = getPackageNameWithSuffix(args.appId, args.appIdSuffix, packageName);
 
   const adbPath = getAdbPath();
   if (args.deviceId) {
@@ -302,6 +312,10 @@ module.exports = {
     command: '--appFolder [string]',
     description: 'Specify a different application folder name for the android source.',
     default: 'app',
+  }, {
+    command: '--appId [string]',
+    description: 'Specify an applicationId to launch after build.',
+    default: '',
   }, {
     command: '--appIdSuffix [string]',
     description: 'Specify an applicationIdSuffix to launch after build.',