Gate binding with `UserManager.isUserUnlocked`

We cannot bind to not direct boot aware apps before that. So delay the
binding until we receive `ACTION_USER_UNLOCKED` (or immediately if we
are unlocked).

Also, delay it to onBootComplete

Fixes: 274467616
Test: manual `adb shell dumpsys activity services` after restart
Test: atest ControlsStartableTest
Change-Id: Ic2c7d1584300fa68c7d53dcea52650cfd83b677b