Use exec for binary execution

Ensure that if run.sh is called directly with an existing mounted
/config, we can correctly execute the server.  This allows us to
manually set the uid/gid of steam and switch the entrypoint, causing the
server binary to be UID 1.  This allows graceful stopping of the server
when `docker stop` is issued.  Testing has unfortunately shown multiple
issues with propagating signals through the sudo call present in init.sh

run.sh

@@ -36,6 +36,7 @@ else
     printf "Skipping update as flag is set\\n"
 fi
 
+mkdir -p "${GAMECONFIGDIR}/Config/LinuxServer" "${GAMECONFIGDIR}/Logs" "${GAMECONFIGDIR}/SaveGames/server" "${GAMESAVESDIR}/server" 
 cp -a "/config/saves/." "/config/backups/"
 cp -a "${GAMESAVESDIR}/server/." "/config/backups" # useless in first run, but useful in additional runs
 rm -rf "${GAMESAVESDIR}/server"
@@ -51,4 +52,4 @@ fi
 
 cd /config/gamefiles || exit 1
 
-Engine/Binaries/Linux/UE4Server-Linux-Shipping FactoryGame -log -NoSteamClient -unattended ?listen -Port="$SERVERGAMEPORT" -BeaconPort="$SERVERBEACONPORT" -ServerQueryPort="$SERVERQUERYPORT" -multihome="$SERVERIP"
+exec Engine/Binaries/Linux/UE4Server-Linux-Shipping FactoryGame -log -NoSteamClient -unattended ?listen -Port="$SERVERGAMEPORT" -BeaconPort="$SERVERBEACONPORT" -ServerQueryPort="$SERVERQUERYPORT" -multihome="$SERVERIP"