Opt-in predicitive back before register the back button

The predictive back infra checks the opt-in status when a callback is registered, and drops the registration if the Application / Activity is not opted-in

Fix: 326627953
Test: manual
Flag: ACONFIG launcher.enable_predictive_back_gesture DISABLED
Change-Id: I8f2e2378d0bf966b3784cf08c12045509b6d5682