session.setModel() missing ReasoningEffort value

[IeuanWalker]

When creating or resuming a session you can set both the model and the ReasoningEffort -

SessionConfig config = new()
{
	Model = defaultModel.Id,
	ReasoningEffort = defaultModel.DefaultReasoningEffort
}

This PR added support for selecting a new model during a session, but missing the ability to set the models ReasoningEffort - #621