Make sure the task bar stays unstashed upon configuration change

So we recreate task bars when configuration is changed, if ENABLE_TASKBAR_NAVBAR_UNIFICATION = true. In order for unstashed state to propagate, we need to save STASHED_IN_APP_AUTO in TaskbarSharedState.

Fixes: 311429718
Test: Unstash the task bar in app, rotate, make sure the task bar stays unstashed
Change-Id: I7db773725ea89976612e9e91af5b6911d0ec5fc0