fix: Drastically simplifies regions (#1400)

### Summary
- [X] Gets rid of the Dtos
- [X] Simplifies the json serializer registration
- [X] Adds a custom `RegionByName` JsonConverter that can look up other regions that have already been registered.


### BREAKING CHANGE
1. **Child regions must appear after their parents in the JSON file**
2. In the regions json file, _"Parent"_ can no longer be just a string. It must be an object that includes the map.
      - ```json
        "Parent": { "Name": "Britain", "Map": "Felucca" }
        ```

Projects/Server/Json/Converters/RegionByNameConverter.cs

@@ -0,0 +1,85 @@
+/*************************************************************************
+ * ModernUO                                                              *
+ * Copyright 2019-2023 - ModernUO Development Team                       *
+ * Email: hi@modernuo.com                                                *
+ * File: RegionByNameConverter.cs                                        *
+ *                                                                       *
+ * This program is free software: you can redistribute it and/or modify  *
+ * it under the terms of the GNU General Public License as published by  *
+ * the Free Software Foundation, either version 3 of the License, or     *
+ * (at your option) any later version.                                   *
+ *                                                                       *
+ * You should have received a copy of the GNU General Public License     *
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>. *
+ *************************************************************************/
+
+using System;
+using System.Text.Json;
+using System.Text.Json.Serialization;
+
+namespace Server.Json;
+
+public class RegionByNameConverter : JsonConverter<Region>
+{
+    public override Region Read(ref Utf8JsonReader reader, Type typeToConvert, JsonSerializerOptions options)
+    {
+        string name = null;
+        Map map = null;
+
+        if (reader.TokenType != JsonTokenType.StartObject)
+        {
+            throw new JsonException("Invalid json for RegionByName");
+        }
+
+        while (true)
+        {
+            reader.Read();
+            if (reader.TokenType == JsonTokenType.EndObject)
+            {
+                break;
+            }
+
+            if (reader.TokenType != JsonTokenType.PropertyName)
+            {
+                throw new JsonException("Invalid json for RegionByName");
+            }
+
+            string property = reader.GetString()?.ToLower();
+
+            if (property != "name" && property != "map")
+            {
+                continue;
+            }
+
+            reader.Read();
+            if (reader.TokenType != JsonTokenType.String)
+            {
+                throw new JsonException($"Value for {property} must be a string");
+            }
+
+            if (property == "name")
+            {
+                name = reader.GetString();
+            }
+            else
+            {
+                map = Map.Parse(reader.GetString());
+            }
+        }
+
+        if (name == null || map == null)
+        {
+            throw new JsonException("Invalid json for RegionByName");
+        }
+
+        return Region.Find(name, map);
+    }
+
+    public override void Write(Utf8JsonWriter writer, Region value, JsonSerializerOptions options)
+    {
+        writer.WriteStartObject();
+        writer.WriteString("Name", value.Name);
+        writer.WriteString("Map", value.Map.Name);
+        writer.WriteEndObject();
+    }
+}

Projects/Server/Json/Converters/RegionByNameConverterFactory.cs

@@ -0,0 +1,28 @@
+/*************************************************************************
+ * ModernUO                                                              *
+ * Copyright 2019-2023 - ModernUO Development Team                       *
+ * Email: hi@modernuo.com                                                *
+ * File: RegionByNameConverterFactory.cs                                 *
+ *                                                                       *
+ * This program is free software: you can redistribute it and/or modify  *
+ * it under the terms of the GNU General Public License as published by  *
+ * the Free Software Foundation, either version 3 of the License, or     *
+ * (at your option) any later version.                                   *
+ *                                                                       *
+ * You should have received a copy of the GNU General Public License     *
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>. *
+ *************************************************************************/
+
+using System;
+using System.Text.Json;
+using System.Text.Json.Serialization;
+
+namespace Server.Json;
+
+public class RegionByNameConverterFactory : JsonConverterFactory
+{
+    public override bool CanConvert(Type typeToConvert) => typeToConvert == typeof(Region);
+
+    public override JsonConverter CreateConverter(Type typeToConvert, JsonSerializerOptions options) =>
+        new RegionByNameConverter();
+}