Replace Newtonsoft.Json with System.Text.Json (#869)

* Converted to use `System.Text.Json`

* Remove Newtonsoft.Json Dependency
Newtonsoft.Json dependency has been removed in favor of System.Text.Json

* Treat MGFXO file as binary

tests/MonoGame.Extended.Tests/Serialization/ColorJsonConverterTests.cs

@@ -0,0 +1,66 @@
+using System;
+using System.IO;
+using System.Text;
+using System.Text.Json;
+using Microsoft.Xna.Framework;
+using MonoGame.Extended.Serialization;
+
+namespace MonoGame.Extended.Tests.Serialization;
+
+public sealed class ColorJsonConverterTests
+{
+    private readonly ColorJsonConverter _converter = new ColorJsonConverter();
+
+    [Fact]
+    public void CanConvert_ColorType_ReturnsTrue()
+    {
+        var colorType = typeof(Color);
+        var result = _converter.CanConvert(colorType);
+        Assert.True(result);
+    }
+
+    [Fact]
+    public void CanConvert_NonColorType_ReturnsFalse()
+    {
+        var otherType = typeof(string);
+        var result = _converter.CanConvert(otherType);
+        Assert.False(result);
+    }
+
+    [Theory]
+    [InlineData("Red", 255, 0, 0, 255)]
+    [InlineData("#FF0000FF", 255, 0, 0, 255)]
+    public void Read_ValidColorJson_ReturnsExpectedColor(string jsonValue, byte r, byte g, byte b, byte a)
+    {
+        var json = $"\"{jsonValue}\"";
+        var reader = new Utf8JsonReader(Encoding.UTF8.GetBytes(json));
+
+        reader.Read();
+        var actual = _converter.Read(ref reader, typeof(Color), new JsonSerializerOptions());
+
+        var expected = new Color(r, g, b, a);
+        Assert.Equal(expected, actual);
+    }
+
+    [Fact]
+    public void Write_ValidColor_WritesExpectedJson()
+    {
+        var expected = "#ff000000";
+        var color = ColorHelper.FromHex(expected);
+        using var stream = new MemoryStream();
+        using var writer = new Utf8JsonWriter(stream);
+
+        _converter.Write(writer, color, new JsonSerializerOptions());
+        writer.Flush();
+        var actual = Encoding.UTF8.GetString(stream.ToArray());
+
+        Assert.Equal($"\"{expected}\"", actual);
+    }
+
+    [Fact]
+    public void Write_NullWrier_ThrowArgumentNullException()
+    {
+        var color = Color.MonoGameOrange;
+        Assert.Throws<ArgumentNullException>(() => _converter.Write(null, color, new JsonSerializerOptions()));
+    }
+}

tests/MonoGame.Extended.Tests/Serialization/RectangleFJsonConverterTest.cs

@@ -1,6 +1,6 @@
 using System.IO;
+using System.Text.Json;
 using MonoGame.Extended.Serialization;
-using Newtonsoft.Json;
 using Xunit;
 
 namespace MonoGame.Extended.Tests.Serialization;
@@ -18,12 +18,15 @@ public class RectangleFJsonConverterTest
     {
         var jsonData = @"
 {
-    box: ""1 1 10 10""
+    ""box"": ""1 1 10 10""
 }
 ";
-        var serializer = new JsonSerializer();
-        serializer.Converters.Add(new RectangleFJsonConverter());
-        var content = serializer.Deserialize<TestContent>(new JsonTextReader(new StringReader(jsonData)));
+        var options = new JsonSerializerOptions
+        {
+            PropertyNameCaseInsensitive = true
+        };
+        options.Converters.Add(new RectangleFJsonConverter());
+        var content = JsonSerializer.Deserialize<TestContent>(jsonData, options);
 
         Assert.Equal(1, content.Box.Left);
         Assert.Equal(1, content.Box.Top);