Create the default network file during startup of network manager

if network file is not on the system then create the default network
file with dhcp enabled.

Resolves openbmc/openbmc#2332

Change-Id: I9e523c76f684dcb2951a0a730f94b11f326b5489
Signed-off-by: Ratan Gupta <ratagupt@in.ibm.com>
diff --git a/network_manager.hpp b/network_manager.hpp
index 0d15fc6..70ed8fc 100644
--- a/network_manager.hpp
+++ b/network_manager.hpp
@@ -94,11 +94,19 @@
          */
         const DHCPConfPtr& getDHCPConf() { return dhcpConf; }
 
-    private:
+        /** @brief create the default network files for each interface
+         *  @detail if force param is true then forcefully create the network
+         *          files otherwise if network file doesn't exist then
+         *          create it.
+         *  @param[in] force - forcefully create the file
+         *  @return true if network file created else false
+         */
+        bool createDefaultNetworkFiles(bool force);
 
         /** @brief restart the systemd networkd. */
         void restartNetwork();
 
+    private:
         /** @brief Persistent sdbusplus DBus bus connection. */
         sdbusplus::bus::bus& bus;