This commit add the ability for ctrld to gather client information,
including mac/ip/hostname, and send to Control-D server through a
config per upstream.
- Add send_client_info upstream config.
- Read/Watch dnsmasq leases files on supported platforms.
- Add corresponding client info to DoH query header
All of these only apply for Control-D upstream, though.
Supported actions:
- start: install and start ctrld as a system service
- stop: stop the ctrld service
- restart: restart ctrld service
- status: show status of ctrld service
- uninstall: remove ctrld from system service
