discover-system-state: add multi-host support

Add HostObjects class to fetch paths of settings d-bus objects under
/xyz/openbmc_project/control/hostX .

Signed-off-by: Potin Lai <potin.lai@quantatw.com>
Change-Id: I1dc55ec389e94e6c85aa7031b304f8c4ed15dc71
diff --git a/host_state_manager.hpp b/host_state_manager.hpp
index c3394f0..0e796f5 100644
--- a/host_state_manager.hpp
+++ b/host_state_manager.hpp
@@ -69,7 +69,7 @@
                 sdbusRule::interface("org.freedesktop.systemd1.Manager"),
             std::bind(std::mem_fn(&Host::sysStateChangeJobNew), this,
                       std::placeholders::_1)),
-        settings(bus), id(id)
+        settings(bus, id), id(id)
     {
         // Enable systemd signals
         subscribeToSystemdSignals();
@@ -303,8 +303,8 @@
     /** @brief Used to subscribe to dbus systemd JobNew signal **/
     sdbusplus::bus::match_t systemdSignalJobNew;
 
-    // Settings objects of interest
-    settings::Objects settings;
+    // Settings host objects of interest
+    settings::HostObjects settings;
 
     /** @brief Host id. **/
     const size_t id = 0;