SSL/TLS supprt in dotnet

[TimRivinius]

Added support for SSL/TLS in dotnet package

I'm not a Java developer and can't add this feature on Java side.

[irmen]

cool, thanks for the contribution!

[irmen]

haven't had the time to test this yet, which I want to do before merging.

[TimRivinius]

I tested it with the Echo Server (Settings made with Environment Variables) and in the Echo test example I simply set the new config items.
When Testing Mutual TLS make sure to use the pfx/pkcs12 format since dotnet does not support seperate pem files for cert and key.

[irmen]

any quick guide on how to generate such keys? I'm not too familiar with it

[TimRivinius]

With openssl you can generate such a file with openssl pkcs12 -export -out certificate.pfx -inkey privateKey.key -in certificate.crt from any normal cert/key combo. You will get 1 file containing both, the key and the cert.
The CACERTS file can be in normal pem format.