requester: Modified MctpDiscovery class

Modified MctpDiscovery class to take list of managers instead of single
fwManager. The change is for adding platform-mc manager.
Added loadStaticEndpoints API for MCTP layer which doesn't implement
/xyz/openbmc_project/MCTP/Endpoint.Interface

The patch is part of implementation of design document below.
https://gerrit.openbmc-project.xyz/c/openbmc/docs/+/47252

Signed-off-by: Gilbert Chen <gilbert.chen@arm.com>
Signed-off-by: Thu Nguyen <thu@os.amperecomputing.com>
Change-Id: I1e1673504583a87f2a9bc3adf76fb49c2dc30254
diff --git a/common/utils.cpp b/common/utils.cpp
index 9eed1be..e9b2c68 100644
--- a/common/utils.cpp
+++ b/common/utils.cpp
@@ -569,6 +569,18 @@
     return bus.call(method).unpack<ObjectValueTree>();
 }
 
+PropertyMap
+    DBusHandler::getDbusPropertiesVariant(const char* serviceName,
+                                          const char* objPath,
+                                          const char* dbusInterface) const
+{
+    auto& bus = DBusHandler::getBus();
+    auto method = bus.new_method_call(serviceName, objPath, dbusProperties,
+                                      "GetAll");
+    method.append(dbusInterface);
+    return bus.call(method, dbusTimeout).unpack<PropertyMap>();
+}
+
 PropertyValue jsonEntryToDbusVal(std::string_view type,
                                  const nlohmann::json& value)
 {