KeyExchange-Key API

This version adds a public Key API. From the CryptographyHelper, you can grab the server's shared key (as client) or a client's shared key (as server). This key is safe to be used for cryptographic purposes.

However! It is recommended to do your own key derrivation from this key to your own key to ensure cryptographic vulnerabilities won't affect the MLAPI protocol encryption and authentication.

It also fixes a bug where garbage bits from the pooled stream would be used to calculate the NetworkConfig hash making it turn out different.