Start Migration from Newtonsoft.Json to System.Text.Json (#1803)

* Start switch to System.Text.Json

* Work on switching to System.Text.Json

* Main work on STJ refactor

* Fix build errors

* Run formatting

* Delete unused file

* Use legacy for two factor providers

* Run formatter

* Add TokenProviderTests

* Run formatting

* Fix merge issues

* Switch to use JsonSerializer

* Address PR feedback

* Fix formatting

* Ran formatter

* Switch to async

* Ensure Enums are serialized as strings

* Fix formatting

* Enqueue single items as arrays

* Remove CreateAsync method on AzureQueueService

test/Core.Test/Models/Data/SendFileDataTests.cs

@@ -0,0 +1,28 @@
+using System.Text.Json;
+using Bit.Core.Models.Data;
+using Bit.Test.Common.Helpers;
+using Xunit;
+
+namespace Bit.Core.Test.Models.Data
+{
+    public class SendFileDataTests
+    {
+        [Fact]
+        public void Serialize_Success()
+        {
+            var sut = new SendFileData
+            {
+                Id = "test",
+                Size = 100,
+                FileName = "thing.pdf",
+                Validated = true,
+            };
+
+            var json = JsonSerializer.Serialize(sut);
+            var document = JsonDocument.Parse(json);
+            var root = document.RootElement;
+            AssertHelper.AssertJsonProperty(root, "Size", JsonValueKind.String);
+            Assert.False(root.TryGetProperty("SizeString", out _));
+        }
+    }
+}