Two fixes for ads behaving differently from config:

1. Test devices now actually register. Admob.Start was notImplemented on both
   platforms and AdmobInit's System.getenv("ADMOB_TEST_DEVICES") isn't populated
   in the native process, so setTestDeviceIds never ran -> registered test
   devices still got real ads. Start now applies the test_devices passed as a
   bridge param (config('admob.test_devices')) via setRequestConfiguration on
   Android + iOS. (Host must call Admob::start().)

2. App-open auto-show is now suppressible. AppOpenLifecycle presents on
   foreground outside any per-request gate, so a previously-loaded app-open
   would still show after an ad-free pass was granted. New
   Admob::setAppOpenSuppressed(bool) + Admob.SetAppOpenSuppressed bridge toggle
   a native kill-switch the lifecycle honours (Android + iOS).

Co-Authored-By: Claude <noreply@anthropic.com>