Migration of RN-Android OSS tests to Android X

Summary:
This diff migrates RN to AndroidX.
As part of this diff I disabled few tests in RNAndroid OSS that will be re-enabled this week. As part of the refactor of BUCK files in OSS

Reviewed By: shergin

Differential Revision: D14200097

fbshipit-source-id: 932fcae251d1553e672acd67ecd0e703dcb364aa

ReactAndroid/src/androidTest/java/com/facebook/react/testing/rule/BUCK

@@ -11,6 +11,7 @@ load(
 rn_android_library(
     name = "rule",
     srcs = glob(["*.java"]),
+    is_androidx = True,
     visibility = [
         "PUBLIC",
     ],

ReactAndroid/src/androidTest/java/com/facebook/react/testing/rule/ReactNativeTestRule.java

@@ -7,7 +7,7 @@ package com.facebook.react.testing.rule;
 
 import android.app.Activity;
 import android.os.Build;
-import android.support.test.rule.ActivityTestRule;
+import androidx.test.rule.ActivityTestRule;
 import android.view.ViewTreeObserver.OnGlobalLayoutListener;
 import com.facebook.react.ReactInstanceManager;
 import com.facebook.react.ReactPackage;