Implemented sensor class

Sensor class was introduced, it monitors
xyz.openbmc_project.Sensor.Value, for change and notifies all
listeners.

Tested:
  - Unit tested with service stub that provides dbus interface
    xyz.openbmc_project.Sensor.Value
  - All changes are delivered to listeners
  - All other unit tests are passing

Change-Id: I8c9d58cc986c1fe2a4d2386815d559814016efa6
Signed-off-by: Krzysztof Grobelny <krzysztof.grobelny@intel.com>
diff --git a/tests/src/test_sensor_cache.cpp b/tests/src/test_sensor_cache.cpp
index 5be9a0d..a3831dc 100644
--- a/tests/src/test_sensor_cache.cpp
+++ b/tests/src/test_sensor_cache.cpp
@@ -1,5 +1,6 @@
 #include "mocks/sensor_mock.hpp"
 #include "sensor_cache.hpp"
+#include "utils/sensor_id_eq.hpp"
 
 #include <initializer_list>
 
@@ -13,13 +14,6 @@
     SensorCache sut;
 };
 
-auto sensorIdEq(interfaces::Sensor::Id id)
-{
-    return AllOf(Field(&interfaces::Sensor::Id::type, Eq(id.type)),
-                 Field(&interfaces::Sensor::Id::service, Eq(id.service)),
-                 Field(&interfaces::Sensor::Id::path, Eq(id.path)));
-}
-
 struct IdParam
 {
     IdParam() = default;