Add support for Predictive Back in CreateUserActivity

Test: atest CreateUserActivityTest
Bug: 254840316
Change-Id: I9d00c114ae38e72f11678dab93d3feaf222463d1
diff --git a/packages/SystemUI/Android.bp b/packages/SystemUI/Android.bp
index 6d54270..540ca04 100644
--- a/packages/SystemUI/Android.bp
+++ b/packages/SystemUI/Android.bp
@@ -223,6 +223,7 @@
         "androidx.test.rules",
         "androidx.test.uiautomator",
         "mockito-target-extended-minus-junit4",
+        "androidx.test.ext.junit",
         "testables",
         "truth-prebuilt",
         "monet",