Add networking configuration

[mborgerson]

The UI tab/components are there but nothing is hooked up. This needs to add the proper net flags to xqemu. Should support port forwarding. Here's a sample partial command line to get started:

-net nic,model=nvnet -net user,hostfwd=tcp:127.0.0.1:8081-:21,hostfwd=tcp:127.0.0.1:731-:731 \

[JayFoxRox]

I think we should remove the MAC text-box and. if anything, it should be a read-only field which displays the EEPROM field; but that still isn't ideal.

I'm not sure what the "Connected to" is for (network speed?). If it is meant for network-speed, it could be combined into the "Cable connected" box probably.

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We also care about socket mode for https://github.com/mborgerson/l2tunnel now. This would probably need another table to add sockets.

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As a stop-gap, it would be interesting to see this configurable via the settings.json (even if the UI might be read-only for now).