#53 - Refactored various components:

- updated the authentication coordinator to use async await
- replaced the UserSession with a ClientProxy (similar to the RoomProxy)
- renamed `completion` to `callback` on the coordinators and view models
- renamed `viewModelResult` to `viewModelAction`
- introduced back UserSession as a user specific service container

Tools/Scripts/Templates/SimpleScreenExample/ElementX/TemplateSimpleScreenViewModelProtocol.swift

@@ -18,6 +18,6 @@ import Foundation
 
 @MainActor
 protocol TemplateSimpleScreenViewModelProtocol {
-    var completion: ((TemplateSimpleScreenViewModelResult) -> Void)? { get set }
+    var callback: ((TemplateSimpleScreenViewModelAction) -> Void)? { get set }
     var context: TemplateSimpleScreenViewModelType.Context { get }
 }