Fix some bugs for robustness.

1. Catch all exceptions when we are trying to read an APK to find the base apk.
We noticed in some error cases, package parser will throw an exception instead
of returning null. We should continue inspecting other apks.
2. Make invalid apk default to allow.

Bug: 145674131
Test: atest AppIntegrityMangaerServiceImpl
Change-Id: I11f2b7bad84c3ee697e01da68f901935db0c4f44