Add file contexts for AdServices APEX

Test: Build
Bug: 220336612
Change-Id: Iab64d228a5edcd3a9f71b59c5adf3a9460cd1947
diff --git a/apex/Android.bp b/apex/Android.bp
index 166c2d3..b85b1f5 100644
--- a/apex/Android.bp
+++ b/apex/Android.bp
@@ -251,6 +251,13 @@
 }
 
 filegroup {
+  name: "com.android.adservices-file_contexts",
+  srcs: [
+    "com.android.adservices-file_contexts",
+  ],
+}
+
+filegroup {
   name: "com.android.car.framework-file_contexts",
   srcs: [
     "com.android.car.framework-file_contexts",