add google maven repo in android project template (#19712)

Summary:
This PR will add Google maven repo to RN project template that contains com.android.support:appcompat-v7:26.1.0, thus fixes `react-native run-android` using version 0.56.0-rc.1

CI is Green - https://circleci.com/gh/dulmandakh/react-native/235

new Android projects will build and run just fine.
Closes https://github.com/facebook/react-native/pull/19712

Differential Revision: D8433730

Pulled By: hramos

fbshipit-source-id: b7d5a1cd5a97b1c4aad2a307158d6dbfcf9a42a5

local-cli/templates/HelloWorld/android/build.gradle

@@ -3,6 +3,10 @@
 buildscript {
     repositories {
         jcenter()
+        maven {
+            url 'https://maven.google.com/'
+            name 'Google'
+        }
     }
     dependencies {
         classpath 'com.android.tools.build:gradle:2.2.3'
@@ -20,5 +24,9 @@ allprojects {
             // All of React Native (JS, Obj-C sources, Android binaries) is installed from npm
             url "$rootDir/../node_modules/react-native/android"
         }
+        maven {
+            url 'https://maven.google.com/'
+            name 'Google'
+        }
     }
 }