Add test for URL resource

[dzeban]

There are tests that check printing from the file. We also need to test that cert is able to print certificate chain from the given URL. The trick is to make it work in isolation so querying some domain is not an option - test must work without internet and also certificate for domain will be replaced sometime and golden output should be changed every 3 months or so.

So the idea is to spin up TLS server in one goroutine and query it from test. Because TLS server is local only self-signed certificate can be used. But this certificate couldn't be verified because cert uses system CA certs pool. So this test will require adding option to cert to use CA cert from file.