zone: Add debug interface to zone dbus path

- Add xyz.openbmc_project.Debug.Pid.Zone interface to fanctrl/zoneX dbus
  to record the PID config name which is driving this zone.

TEST:
```
busctl introspect xyz.openbmc_project.State.FanCtrl /xyz/openbmc_project/settings/fanctrl/zone0 xyz.openbmc_project.Debug.Pid.Zone
NAME                               TYPE      SIGNATURE RESULT/VALUE FLAGS
.Leader                            property  s         "CPU0_PID"   emits-change
```

Signed-off-by: Harvey Wu <Harvey.Wu@quantatw.com>
Change-Id: I6fcfa596eec6b51a7727c2a01e7d36e3698eebcf
diff --git a/test/pid_zone_unittest.cpp b/test/pid_zone_unittest.cpp
index 8c55a70..391d026 100644
--- a/test/pid_zone_unittest.cpp
+++ b/test/pid_zone_unittest.cpp
@@ -26,6 +26,7 @@
 using ::testing::StrEq;
 
 static std::string modeInterface = "xyz.openbmc_project.Control.Mode";
+static std::string debugZoneInterface = "xyz.openbmc_project.Debug.Pid.Zone";
 static std::string enableInterface = "xyz.openbmc_project.Object.Enable";
 
 namespace
@@ -60,6 +61,8 @@
     std::vector<std::string> properties;
     SetupDbusObject(&sdbus_mock_mode, defer, objPath, modeInterface, properties,
                     &d);
+    SetupDbusObject(&sdbus_mock_mode, defer, objPath, debugZoneInterface,
+                    properties, &d);
 
     std::string sensorname = "temp1";
     std::string pidsensorpath = "/xyz/openbmc_project/settings/fanctrl/zone1/" +
@@ -100,6 +103,8 @@
 
         SetupDbusObject(&sdbus_mock_mode, defer, objPath, modeInterface,
                         properties, &property_index);
+        SetupDbusObject(&sdbus_mock_mode, defer, objPath, debugZoneInterface,
+                        properties, &property_index);
 
         SetupDbusObject(&sdbus_mock_enable, defer, pidsensorpath.c_str(),
                         enableInterface, propertiesenable,