Add ReportManager and Report unit tests

Introduced ReportFactory to seperate Report and ReportManager
unit tests. Implemented mocks for Report, ReportManager and
ReportFactory classes. Added tests for DBus Properties and Methods
provided by telemetry service.

Tested:
 - Ran unit-tests with success

Change-Id: I1860e280d26ee4becc52de98dd65e5697d26b376
Signed-off-by: Wludzik, Jozef <jozef.wludzik@intel.com>
diff --git a/meson.build b/meson.build
index d3472da..165eb2d 100644
--- a/meson.build
+++ b/meson.build
@@ -74,6 +74,7 @@
         'src/main.cpp',
         'src/persistent_json_storage.cpp',
         'src/report.cpp',
+        'src/report_factory.cpp',
         'src/report_manager.cpp',
         'src/sensor.cpp',
         'src/sensor_cache.cpp',