[TIMOB-18159] CLI: Implement node connectivity tests from titanium-connection-test in ti setup check

Replace the existing network connectivity tests in ti setup check with those from the https://github.com/appcelerator/titanium-connection-test project. Connections should be made via the proxy (if any) as configured with the existing CLI network configuration functionality. The set of URLs to check should be stored in an external file for easy updating. If all sites are reachable, output a simple message, like: ✓ Network connection test If sites are unreachable, output a message for each site that cannot be access, like: ✕ api.appcelerator.net is unreachable