Quick affordances crash fix for secondary users.

This CL fixes a few issues that are making lock screen customization and
lock screen shortcuts unavailable for secondary users.

The attached bug occurs because we're querying state off the main
thread. The first part of the CL modifies our content provider to move
its querying onto the main thread while blocking the calling thread
(which is a background thread).

After fixing that, several problems emerged. When we query for
affordances, we iterate through each affordance configuration and check
its "picker state". For the camera and flashlight affordances, this was
problematic.

The camera affordance had a complex dependnecy chain that ended up
relying on DevicePolicyManager which was not being set until after the
CoreStartable for CoreSurfacesImpl ran its start() method, which doesn't
happen at all for secondary users. I worked around that issue by
simplifying the use-case in the camera affordance to just directly check
whether the device has camera hardware. If an admin doesn't allow it, I
presume that opening the camera app will fail.

The flashlight affordance triggered a broadcast to be sent for
FLASHLIGHT_CHANGED. The problem is that this is a protected broadcast
designed to prevent non-framework apps from sending it; which also means
that our secondary user process does not have the necessary security
permission to send it, causing the SystemUI process to crash. I removed the broadcast sending. This was not needed by the flashlight affordance or
by the quick setting or by the smart space "turn off flashlight" link.
Also, the unit test for the controller passes.

Fix: 265245824
Test: unit tests still pass, some were updated to pass
Test: manully verified the wallpaper picker loads and shows all
affordance options for both primary and secondary users
Test: manually verified that selecting any of the affordance options in
wallpaper picker produces fully working experiences for the lock screen
shortcuts (tested all on both primary and secondary user)
Test: manually verified that flashlight toggles on and off correctly
from the lock screen shortcut, smart space, and quick settings tile, for
primary and secondary users alike

Change-Id: Ifb2b47e7d521c67378b2c64f6f32f863319a5b5d