Add a new system service for app search management.

This change adds appsearch-service to base system and media system.

Bug: 142567528
Test: atest cts/tests/appsearch/src/com/android/cts/appsearch/AppSearchManagerTest.java
Change-Id: I4c7b2a2fb7e58b6796a4e5f2034f70d0dc706e0f