Add network support

[freswa]

As implemented in libimobiledevice/libimobiledevice#728 for the Apple usbmuxd, the last missing building block to allow wifi connectivity on linux is usbmuxd. There is an implementation here which doesn't seem to be maintained.
Are there any plans to implement network connectivity in usbmuxd?

[NyaMisty]

I've got an idea.
maybe usbmuxd is considering a better approach to handle mDNS, which doesn't have an cross-platform library.
We can actually add an interface to usbmuxd. The interface accepts a network device info, and add it to device list. When first usbmuxd_connect called, we start heartbeat, and when the last connection dies, we stop the heartbeat.