[dotnet] Mark network request id as non-nullable (#17082)

Author: nvborisenko

dotnet/src/webdriver/HttpRequestData.cs

@@ -56,5 +56,5 @@ public HttpRequestData()
     /// <summary>
     /// Gets the ID of the HTTP request.
     /// </summary>
-    public string? RequestId { get; internal set; }
+    public string RequestId { get; internal set; } = null!;
 }

dotnet/src/webdriver/HttpResponseData.cs

@@ -37,7 +37,7 @@ public HttpResponseData()
     /// <summary>
     /// Gets or sets the ID of the request that generated this response.
     /// </summary>
-    public string? RequestId { get; set; }
+    public string RequestId { get; set; } = null!;
 
     /// <summary>
     /// Gets or sets the URL of the HTTP response.

dotnet/test/remote/RemoteSessionEventTests.cs

@@ -34,7 +34,7 @@ public void CanFireSessionEventWithPayload()
         {
             remoteDriver.Url = simpleTestPage;
 
-            var payload = new Dictionary<string, object?>
+            var payload = new Dictionary<string, object>
             {
                 { "testName", "LoginTest" },
                 { "error", "Element not found" }