network_config: Write configs from parser

Tested: Booted up a clean RWFS and saw that the configs were written
correctly from networkd.

Change-Id: I0915571f87ec803b127cd8c51af37832a2720fdd
Signed-off-by: William A. Kennington III <wak@google.com>
diff --git a/src/network_config.hpp b/src/network_config.hpp
index 7260ca2..a5c7300 100644
--- a/src/network_config.hpp
+++ b/src/network_config.hpp
@@ -1,4 +1,5 @@
-#include <string>
+#include <filesystem>
+#include <string_view>
 
 namespace phosphor
 {
@@ -7,8 +8,8 @@
 
 namespace bmc
 {
-void writeDHCPDefault(const std::string& filename,
-                      const std::string& interface);
+void writeDHCPDefault(const std::filesystem::path& filename,
+                      std::string_view interface);
 }
 
 } // namespace network