sensor-mon: Threshold alarm logger framework

Add the new class ThresholdAlarmLogger that will watch the Warning,
Critical, and PerformanceLoss sensor threshold D-Bus interfaces and
create event logs when their alarm properties set and clear.

This commit just creates the class with its three sdbusplus match
objects to watch those interfaces.

Change-Id: I67c629bcabe059952c2029dc034daace9b88f051
Signed-off-by: Matt Spinler <spinler@us.ibm.com>
diff --git a/sensor-monitor/main.cpp b/sensor-monitor/main.cpp
index bf1bf17..9b901f5 100644
--- a/sensor-monitor/main.cpp
+++ b/sensor-monitor/main.cpp
@@ -14,6 +14,7 @@
  * limitations under the License.
  */
 #include "shutdown_alarm_monitor.hpp"
+#include "threshold_alarm_logger.hpp"
 
 #include <sdbusplus/bus.hpp>
 #include <sdeventplus/event.hpp>
@@ -28,5 +29,7 @@
 
     ShutdownAlarmMonitor shutdownMonitor{bus, event};
 
+    ThresholdAlarmLogger logger{bus, event};
+
     return event.loop();
 }