Expose Method "type/kind" for ScmMethodProvider #8037
Description
Original discussion: openai/openai-dotnet#549 (comment)
It has been a common scenario to have to check the type of method when using a visitor to mutate a ScmMethodProvider instance. Rather than having the consumer adding logic to decide if a method is a client method, we should consider exposing an API on ScmMethodProvider to signal what kind of client method it is: ie: Protocol, Convenience, CreateRequest.
We could consider making this type public https://github.com/microsoft/typespec/blob/main/packages/http-client-csharp/generator/Microsoft.TypeSpec.Generator.ClientModel/src/Providers/RestClientProvider.cs#L777-L782