Change the way we handle app and installer certificates to be prepared
for the case that there might be multiple certificates signing the app.

Bug: 148373316
Test: atest frameworks/base/core/tests/coretests/src/android/content/integrity
Test: atest frameworks/base/services/tests/servicestests/src/com/android/server/integrity
Change-Id: Ic1e86aeff6c087266739682fe4fe206200a87420
11 files changed