Check target api version before crashing apps.

All foreground service notifications need to be posted to a valid
notification channel, but only crash apps that don't provide a
valid notification if they target O_MR1+.

Fixes: 66905243
Test: manual, open apps with invalid notifications that do and don't
target O_MR1.

Change-Id: I60897302bf9806cba0e0be365e65c5e8c4ef4806