Refactor credssp sequence to remove dependency on clientconnector

[msabansal]

Refactored CredsspSequence to remove direct dependency on ClientConnector. This allows CredSSPSequence to be reused in cases where one doesn't necessarily create a clientconnector. As an example i am building a rust POC that performs a MITM for an RDP connection and don't need to create a client connector directly.

[CBenoit]

Thank you! I'm currently on vacation, I'll review next week!