0.37.4 - List<T> parameters no longer break service extensions

Fixed

• A List<T> parameter on a meta method broke the build. {Service}ServiceExtensions.g.cs writes parameter types exactly as the interface spelled them, but emitted only using System; — so an unqualified collection failed to resolve, while the ApiClient and server dispatcher rendering the same signature compiled fine. The file now carries System.Collections.Generic and System.Threading.Tasks like its two siblings.