Emit signal if CollectionStatus property changes

This commit implements changes to emit signal if "CollectionStatus"
property changes.

Test:
```
- Use dbus-monitor to monitor property changes on /com/ibm/VPD/Manager
  path
- Use busctl set-property to update "CollectionStatus" property value
  and observe that dbus-monitor detects signal
```

Change-Id: I9b155da261f106ebdaa25d10f807e4de7df862e9
Signed-off-by: Souvik Roy <souvikroyofficial10@gmail.com>
diff --git a/vpd-manager/src/manager.cpp b/vpd-manager/src/manager.cpp
index caf8c40..f57596c 100644
--- a/vpd-manager/src/manager.cpp
+++ b/vpd-manager/src/manager.cpp
@@ -125,7 +125,11 @@
         iFace->register_property_rw<std::string>(
             "CollectionStatus", sdbusplus::vtable::property_::emits_change,
             [this](const std::string& l_currStatus, const auto&) {
-                m_vpdCollectionStatus = l_currStatus;
+                if (m_vpdCollectionStatus != l_currStatus)
+                {
+                    m_vpdCollectionStatus = l_currStatus;
+                    m_interface->signal_property("CollectionStatus");
+                }
                 return true;
             },
             [this](const auto&) { return m_vpdCollectionStatus; });