Add AppComponentFactory API

API to allow some classloader control over instantiation of
items from application's manifest. Unlike the first attempt
this does not encourage developers to extend Application, it simply
provides a small surface to allow control over the creation of objects
like Activities, Services, Receivers, and Providers.

Test: manual
Bug: 70623879
Change-Id: Idcab7c60f54ce3f4575ac29dcdcae321cf458bf3