Use the official JSON parser (#1151)

This remove Utf8son and JsonPrettyPrinter dependencies.

NOTE: the standard JSON parser doesn't support configurable
indentation, as a result, all the pretty printed JSON are indented with 2
spaces.

Ryujinx.Common/Utilities/JsonHelper.cs

@@ -0,0 +1,106 @@
+using System.IO;
+using System.Text;
+using System.Text.Json;
+using System.Text.Json.Serialization;
+
+namespace Ryujinx.Common.Utilities
+{
+    public class JsonHelper
+    {
+        public static JsonNamingPolicy SnakeCase { get; }
+
+        private class SnakeCaseNamingPolicy : JsonNamingPolicy
+        {
+            public override string ConvertName(string name)
+            {
+                if (string.IsNullOrEmpty(name))
+                {
+                    return name;
+                }
+
+                StringBuilder builder = new StringBuilder();
+
+                for (int i = 0; i < name.Length; i++)
+                {
+                    char c = name[i];
+
+                    if (char.IsUpper(c))
+                    {
+                        if (i == 0 || char.IsUpper(name[i - 1]))
+                        {
+                            builder.Append(char.ToLowerInvariant(c));
+                        }
+                        else
+                        {
+                            builder.Append("_");
+                            builder.Append(char.ToLowerInvariant(c));
+                        }
+                    }
+                    else
+                    {
+                        builder.Append(c);
+                    }
+                }
+
+                return builder.ToString();
+            }
+        }
+
+        static JsonHelper()
+        {
+            SnakeCase = new SnakeCaseNamingPolicy();
+        }
+
+        public static JsonSerializerOptions GetDefaultSerializerOptions(bool prettyPrint = false)
+        {
+            JsonSerializerOptions options = new JsonSerializerOptions
+            {
+                DictionaryKeyPolicy  = SnakeCase,
+                PropertyNamingPolicy = SnakeCase,
+                WriteIndented        = prettyPrint,
+                AllowTrailingCommas  = true,
+                ReadCommentHandling  = JsonCommentHandling.Skip
+            };
+
+            options.Converters.Add(new JsonStringEnumConverter());
+
+            return options;
+        }
+
+        public static T Deserialize<T>(Stream stream)
+        {
+            using (BinaryReader reader = new BinaryReader(stream))
+            {
+                return JsonSerializer.Deserialize<T>(reader.ReadBytes((int)(stream.Length - stream.Position)), GetDefaultSerializerOptions());
+            }
+        }
+
+        public static T DeserializeFromFile<T>(string path)
+        {
+            return Deserialize<T>(File.ReadAllText(path));
+        }
+
+        public static T Deserialize<T>(string json)
+        {
+            return JsonSerializer.Deserialize<T>(json, GetDefaultSerializerOptions());
+        }
+
+        public static void Serialize<TValue>(Stream stream, TValue obj, bool prettyPrint = false)
+        {
+            using (BinaryWriter writer = new BinaryWriter(stream))
+            {
+                writer.Write(SerializeToUtf8Bytes(obj, prettyPrint));
+            }
+        }
+
+        public static string Serialize<TValue>(TValue obj, bool prettyPrint = false)
+        {
+            return JsonSerializer.Serialize(obj, GetDefaultSerializerOptions(prettyPrint));
+        }
+
+        public static byte[] SerializeToUtf8Bytes<T>(T obj, bool prettyPrint = false)
+        {
+            return JsonSerializer.SerializeToUtf8Bytes(obj, GetDefaultSerializerOptions(prettyPrint));
+        }
+    }
+}