New script to obtain actual online DNS servers supporting v2 protocol

[jaromil]

The old CSV file understood by dnscrypt-proxy v2 C++ is not up to date and a lot of things have changed, among them the birth of the "DNS stamp" protocol https://github.com/DNSCrypt/dnscrypt-proxy/wiki/stamps which is a base64url encoded string containing all information for each server.

This needs a script to use online information and compile a CSV that is understood by our dnscrypt-proxy so that it can be easily configured. The current list of online v2 servers actually works well, one can just try to:

• pick one from https://github.com/DNSCrypt/dnscrypt-resolvers/tree/master/v2
• decode the DNS stamp with https://dnscrypt.info/stamps/
• configure it by command-line arguments or inside dnscrypt-proxy.conf

For example at the time of writing this issue this v2 server works well with dnscrypt-proxy:

ProviderName    2.dnscrypt-cert.ams-dnscrypt-nl
ProviderKey     a5874bdaf4168298fbec1c9c997502be5a3946fdd71b2e7ef3d48e2777acd45a
ResolverAddress 89.38.131.38:4343