TorchService: close all opened cameras

When the torch is toggled on and then off very quickly, the camera can
still be opened and we never actually end up closing it.

Also reset the torch camera id when we tear the torch down.

Change-Id: I0175e8074edfc89e70f3278649d0ed8f69fb0a71
Signed-off-by: Roman Birg <roman@cyngn.com>