AIDL effect: Add default Effect factory implementation to platform sepolicy

Add example implementation services: IFactory under android.hardware.audio.effect.
An audio HAL AIDL example service will register with the default implementations.

Bug: 238913361
Test: m, and flash with Pixel 6a.

Change-Id: Ib331899fd47b6b334b120e20617174d01e71ddb8
diff --git a/private/service_contexts b/private/service_contexts
index aa90983..0e9d4e8 100644
--- a/private/service_contexts
+++ b/private/service_contexts
@@ -1,5 +1,6 @@
 android.hardware.audio.core.IConfig/default                          u:object_r:hal_audio_service:s0
 android.hardware.audio.core.IModule/default                          u:object_r:hal_audio_service:s0
+android.hardware.audio.effect.IFactory/default                       u:object_r:hal_audio_service:s0
 android.hardware.authsecret.IAuthSecret/default                      u:object_r:hal_authsecret_service:s0
 android.hardware.automotive.evs.IEvsEnumerator/hw/0                  u:object_r:hal_evs_service:s0
 android.hardware.boot.IBootControl/default                           u:object_r:hal_bootctl_service:s0