Fixed NPE and problem in which custom AuthenticationMechanisms aren't used

The DeploymentInfo wraps an AuthenticationMechanism with a
ImmediateAuthenticationMechanismFactory.  However, that factory always returns
null when create() is called.  Fix is to simply returns the AuthenticationMechanism
that was provided to it during construction.
WFLY-2810 Only renegotiate SSL session to get client cert if authentication is actually required