Always specify TypeNameHandling for types under Dalamud assembly (#1910)

LoadForType{T} intentionally does not specify TypeNameHandling which
seemingly is required for handling inheritance for nested properties.
Added a custom JsonConverter that will force TypeNameHandling=Objects
for types under Dalamud assembly, as a quick workaround for forcing font
related types to be correctly handled during deserialization.

Dalamud/Configuration/PluginConfigurations.cs

@@ -1,4 +1,5 @@
 using System.IO;
+using System.Reflection;
 
 using Dalamud.Storage;
 using Newtonsoft.Json;
@@ -116,9 +117,18 @@ public sealed class PluginConfigurations
     /// <returns>Plugin Configuration.</returns>
     public T LoadForType<T>(string pluginName) where T : IPluginConfiguration
     {
-        var path = this.GetConfigFile(pluginName);
+        if (this.GetConfigFile(pluginName) is not { Exists: true } path)
+            return default;
 
-        return !path.Exists ? default : JsonConvert.DeserializeObject<T>(File.ReadAllText(path.FullName));
+        return JsonConvert.DeserializeObject<T>(
+            File.ReadAllText(path.FullName),
+            new JsonSerializerSettings
+            {
+                Converters =
+                [
+                    DalamudAssemblyTypeNameForcingJsonConverter.Instance,
+                ],
+            });
 
         // intentionally no type handling - it will break when updating a plugin at runtime
         // and turns out to be unnecessary when we fully qualify the object type
@@ -162,4 +172,33 @@ public sealed class PluginConfigurations
     }
 
     private DirectoryInfo GetDirectoryPath(string pluginName) => new(Path.Combine(this.configDirectory.FullName, pluginName));
+
+    private class DalamudAssemblyTypeNameForcingJsonConverter : JsonConverter
+    {
+        public static readonly DalamudAssemblyTypeNameForcingJsonConverter Instance = new();
+
+        private static readonly Assembly DalamudAssembly = typeof(DalamudAssemblyTypeNameForcingJsonConverter).Assembly;
+
+        private static readonly JsonSerializer TypeNameForcingJsonConverterDefaultSerializer = new()
+        {
+            TypeNameAssemblyFormatHandling = TypeNameAssemblyFormatHandling.Simple,
+            TypeNameHandling = TypeNameHandling.Objects,
+        };
+
+        private DalamudAssemblyTypeNameForcingJsonConverter()
+        {
+        }
+
+        public override void WriteJson(JsonWriter writer, object? value, JsonSerializer serializer) =>
+            TypeNameForcingJsonConverterDefaultSerializer.Serialize(writer, value);
+
+        public override object? ReadJson(
+            JsonReader reader,
+            Type objectType,
+            object? existingValue,
+            JsonSerializer serializer) =>
+            TypeNameForcingJsonConverterDefaultSerializer.Deserialize(reader, objectType);
+
+        public override bool CanConvert(Type objectType) => objectType.Assembly == DalamudAssembly;
+    }
 }