frameworks/base: switch CameraService to a HAL module

This patch changes CameraService to load a camera HAL module, instead of
linking directly against a library that implements the CameraHardwareInterface
class.

CameraHardwareInterface no longer defines the API to the camera HAL.  Instead,
this is now in HAL header hardware/camera.h.  We keep CamerHardwareInterface as
a class local to CameraService, which wraps around the new HAL calls.  In the
future, we may remove this class entirely and have CameraService call the HAL
methods directly.

Change-Id: I5c61ac40078fc0b50bbac5881a556fe6c8837641
Signed-off-by: Iliyan Malchev <malchev@google.com>