Get bluetooth state on the BluetoothRouteManager looper

When calling getCurrentState() on a state machine from outside its
looper, an ArrayOutOfBoundsException may occur if the state machine is
mid-transition. This change moves the call to getCurrentState into a
Runnable that's run on the looper.

Change-Id: I079552541367733bad5aad1ca6753529f0043143
Fixes: 37224925
Test: manual