New system service: search_ui_service

- Update policy for new system service, used for Launcher/Apps to
fetch and render search results in their UI.

Bug: 162234997
Test: manual verification ($ adb shell service list)


Reference CL: aosp/831251

Change-Id: If3ae22aa2ad1d13aeac3dfefc5244db4b1734d96
diff --git a/private/service_contexts b/private/service_contexts
index 91da637..93a6e32 100644
--- a/private/service_contexts
+++ b/private/service_contexts
@@ -198,6 +198,7 @@
 samplingprofiler                          u:object_r:samplingprofiler_service:s0
 scheduling_policy                         u:object_r:scheduling_policy_service:s0
 search                                    u:object_r:search_service:s0
+search_ui                                 u:object_r:search_ui_service:s0
 secure_element                            u:object_r:secure_element_service:s0
 sec_key_att_app_id_provider               u:object_r:sec_key_att_app_id_provider_service:s0
 sensorservice                             u:object_r:sensorservice_service:s0