Move JDC initialization from main to lib

[jbesraa]

I am trying to write some tests running the whole flow, and noticed that JDC initialization is happening inside main.rs rather than lib.rs which makes it not very modular. I propose to move the initialization to lib so it could be exported and used in different context, like testing

[Fi3]

whatever function will end up initializing the role should take async streams of messages not addresses

[jbesraa]

@Fi3 Could you please comment here #993 with a bit more details?

[Fi3]

It was just a generic comment about make it more modular. Instead of open the socket on initialization, passing a stream of messages so we decouple actual role logic from tansport layer and encryption layer. This is useful for example if I want to initialize inside my application, and somewhere else in the application I already received and decrypted the messages. As I said above is a generic comment about this issue. Not sure if is suited for your PR or not.

[jbesraa]

Done at #993