Using the authenticated user when posting questions and answers

Now that our REST API knows about the user interacting with it, we can use this to post the correct user against questions and answers. Let's carry out the following steps:

1. We'll start by adding the following using statements in QuestionsController.cs:

   using System.Security.Claims;
   using Microsoft.Extensions.Configuration;
   using System.Net.Http;
   using System.Text.Json;

2. Let's focus on posting a question first by posting it with the authenticated user's ID:

   public async ... 
     PostQuestion(QuestionPostRequest 
      questionPostRequest)
   {
     var savedQuestion = 
       await _dataRepository.PostQuestion(new 
         QuestionPostFullRequest
       {
         Title = questionPostRequest.Title,
         Content = questionPostRequest.Content,
    &...