Enable IPv6 tests with HTTPS proxy

[bliuchak]

We have IPv6 test cases that works with HTTP proxy server but don't with HTTPS. The problem is in pre-historic version of got-scraping library we're using there.

In general IPv6 with HTTPS proxy should work with no issue as it shares the same logic as HTTP proxy, however I can't proof it in tests.

Solution

• Repalce got-scraping by impit-node or something else that supports HTTPS proxy and SOCKS.
• Uncomment IPv6 related test cases at tests/server.js.
• Make sure that IPv6 test cases works with HTTPS proxy.