.Net: Consider adding Config classes for use with IKernelBuilder and IServiceCollection AddXXX methods

[markwallace-microsoft]

One problem with the IKernelBuilder and IServiceCollection AddXXX extension methods is that they all have a very long list of parameters. So adding new parameters is a breaking change and we are inclined to keep the existing parameter order (to reduce impact of the breaking change) even if it doesn't make sense.

The goal of this task is to consider adding XXXConfig classes and add new extension methods which just take an instance of XXXConfig. All of the old extension methods can be refactored to call this.