Use androidx.test instead of android.support.test

This CL mechanically changes package name of AndroidJUnitRunner, test
annotation classes, test filter classes, and etc. from android.support.test
to androidx.test.

This CL also copies WidgetTestUtils#runOnMainAndDrawSync() helper method
from CTS and eliminates compatibility-device-util from dependency.

Bug: None
Exempt-From-Owner-Approval: Large-scale refactor
Test: Run all non-flaky presubmit tests in FrameworksCoreTests
  $ tradefed.sh run commandAndExit FrameworksCoreTests \
        --include-annotation android.platform.test.annotations.Presubmit \
	--exclude-annotation androidx.test.filters.FlakyTest
  430 tests pass.
Change-Id: Ia65c4f643961afaa01c2c8d4b271712e574eb45c
diff --git a/core/tests/coretests/src/android/provider/SettingsBackupTest.java b/core/tests/coretests/src/android/provider/SettingsBackupTest.java
index df4600e..667519c 100644
--- a/core/tests/coretests/src/android/provider/SettingsBackupTest.java
+++ b/core/tests/coretests/src/android/provider/SettingsBackupTest.java
@@ -27,8 +27,9 @@
 import static java.lang.reflect.Modifier.isStatic;
 
 import android.platform.test.annotations.Presubmit;
-import android.support.test.filters.SmallTest;
-import android.support.test.runner.AndroidJUnit4;
+
+import androidx.test.filters.SmallTest;
+import androidx.test.runner.AndroidJUnit4;
 
 import org.junit.Test;
 import org.junit.runner.RunWith;