Add apex_available for AdServices

This CL enables apex availability for AdServices, which depends on this
package via build targets being added in tflite-support.

Test: m
Bug: 228842813, 233280325
Change-Id: Id9ac0fe116fd3ae161a214053f4d218070d24404

Android.bp

diff --git a/Android.bp b/Android.bp
index 32b84f8..53ef27c 100644
--- a/Android.bp
+++ b/Android.bp
@@ -41,6 +41,7 @@
         "com.android.neuralnetworks",
         "test_com.android.neuralnetworks",
         "com.android.extservices",
+        "com.android.adservices",
     ],
 }