MultiHal 2.0 - Get sensors list from subhals

Implement SubHal constructors. The default ctor will get the SubHal
object pointers from dynamic libraries. The test ctor will take a vector
of SubHal objects. Implment the HalProxy getSensorsList method which
will return all the sensors from the subhal objects. Create one unit
test for getSensorsList as well.

Bug: 136511617
Test: Flashed onto device and observed proper logs for both test
subhals. Also, passed getSensorsList test.

Change-Id: I6e8ca4883c50daabbd7b0955d3664f66b6cd74bf
diff --git a/sensors/2.0/multihal/include/SubHal.h b/sensors/2.0/multihal/include/SubHal.h
index 75e93a1..e84cba5 100644
--- a/sensors/2.0/multihal/include/SubHal.h
+++ b/sensors/2.0/multihal/include/SubHal.h
@@ -137,6 +137,7 @@
  * sub-HALs can continue to use the lower 3 bytes of the handle.
  */
 class ISensorsSubHal : public ISensors {
+  public:
     // The ISensors version of initialize isn't used for multihal. Instead, sub-HALs must implement
     // the version below to allow communciation logic to centralized in the HalProxy
     Return<Result> initialize(