[test] add expect tests for sntp, mac, netif, and more (#5140)

Also does some minor enhancements.

.github/workflows/simulation.yml

@@ -189,8 +189,8 @@ jobs:
       uses: codecov/codecov-action@v1
     - name: Run TUN Mode
       run: |
-        sudo apt-get install --no-install-recommends -y dnsmasq bind9-host
-        sudo systemctl start dnsmasq
+        sudo apt-get install --no-install-recommends -y dnsmasq bind9-host ntp
+        sudo systemctl start dnsmasq ntp
         host ipv6.google.com 127.0.0.1
         echo 'listen-address=::1' | sudo tee /etc/dnsmasq.conf
         echo 0 | sudo tee /proc/sys/net/ipv6/conf/all/disable_ipv6