Use tag ids for testID

Summary: View tags are currently used for end-to-end test IDs. We'd like to overload the tag field with other information such as nativeID (for native refs) and transitionID (for shared element transitions) in the future. Added a key for testID's tag

Reviewed By: AaaChiuuu

Differential Revision: D4833045

fbshipit-source-id: c2f9371c9a3dbb2411e114f4f096f723ac3132c0

ReactAndroid/src/main/res/BUCK

@@ -27,4 +27,13 @@ android_resource(
     ],
 )
 
+android_resource(
+    name = "uimanager",
+    package = "com.facebook.react",
+    res = "views/uimanager",
+    visibility = [
+        "PUBLIC",
+    ],
+)
+
 # New resource directories must be added to react-native-github/ReactAndroid/build.gradle

ReactAndroid/src/main/res/views/uimanager/values/ids.xml

@@ -0,0 +1,5 @@
+<?xml version="1.0" encoding="utf-8"?>
+<resources>
+  <!-- tag is used to store the testID tag -->
+  <item type="id" name="react_test_id"/>
+</resources>