Create helper methods for specifying face creation via topology

and changes to enable users to run NLSR in Mini-NDN-Wifi.

Refs: #5232
Change-Id: Iac8bd170f34985aa2b7ee080033a6ceaf334bd0c

topologies/wifi/nlsr_wifi_example.conf

@@ -0,0 +1,20 @@
+[stations]
+sta1: range=50
+sta2: range=50
+sta3: range=50
+sta4: range=50
+[cars]
+
+[accessPoints]
+ap1: position=50,50,50 range=50
+
+[links]
+sta1:ap1 delay=10ms
+sta2:ap1 delay=10ms
+sta3:ap1 delay=10ms
+sta4:ap1 delay=10ms
+
+[faces]
+sta1:sta2 cost=42
+sta2:sta4 _
+sta3:sta1 _