common: extract handleInterfaceAdded

The function is extracted from initDevices to decouple it from iterating
over the object mapper response.

Code is only moved and not changed.

Tested: Unit Tests Pass

Change-Id: I5d776818ca1bd7fb335bc540b07ff12993c1125e
Signed-off-by: Alexander Hansen <alexander.hansen@9elements.com>
diff --git a/common/include/software_manager.hpp b/common/include/software_manager.hpp
index 1e0a427..4cf3419 100644
--- a/common/include/software_manager.hpp
+++ b/common/include/software_manager.hpp
@@ -53,6 +53,10 @@
     sdbusplus::async::context& ctx;
 
   private:
+    sdbusplus::async::task<void> handleInterfaceAdded(
+        const std::string& service, const std::string& path,
+        const std::string& interface);
+
     // this is appended to the common prefix to construct the dbus name
     std::string serviceNameSuffix;