Verify `loadingPackageName` on `notifyDexLoad`.

notifyDexLoad is a PM API callable from an app's process. The arguments
are provided by the app and shouldn't be blindly trusted. This change
verifies `loadingPackageName` against calling UID.

Bug: 253570365
Test: Disable AppZygote preloading, start Chrome, and see dex load
  report from both isolated process and non-isolated process being
  accepted (no "Invalid dex load report" warning).
Change-Id: I5d2390ed643f5202b3cdb088795d026dc8fa51df