feat(inss): add optional gslt to start parameters

lgsm/config-default/config-lgsm/inssserver/_default.cfg

@@ -19,9 +19,14 @@ defaultmap="Canyon"
 defaultscenario="Scenario_Crossing_Push_Security"
 maxplayers="28"
 
+## Game Server Login Token (GSLT): Optional
+# GSLT can be used for running a public server.
+# More info: https://docs.linuxgsm.com/steamcmd/gslt
+gslt=""
+
 ## Server Parameters | https://docs.linuxgsm.com/configuration/start-parameters#additional-parameters
 ## Parameter Docs | https://mod.io/g/insurgencysandstorm/r/server-admin-guide
-startparameters="${defaultmap}?Scenario=${defaultscenario}?MaxPlayers=${maxplayers} -Port=${port} -QueryPort=${queryport} -hostname='${servername}' -Rcon -RconPassword=${rconpassword} -RconListenPort=${rconport} -log"
+startparameters="${defaultmap}?Scenario=${defaultscenario}?MaxPlayers=${maxplayers} -Port=${port} -QueryPort=${queryport} -hostname='${servername}' -Rcon -RconPassword=${rconpassword} -RconListenPort=${rconport} -GSLTToken=${gslt} -log"
 
 #### LinuxGSM Settings ####