fix: Moves codegen to its own repo (#918)

- [X] Replace serialization generator with nuget
- [X] Replace schema migration with dotnet bool
- [X] Add ability to run migrations in VS/Rider using a project build

Projects/Schema Migrations/Run Schema Migrations.csproj

@@ -0,0 +1,13 @@
+<Project Sdk="Microsoft.NET.Sdk">
+    <PropertyGroup>
+      <RootNamespace>Schema_Migrations</RootNamespace>
+    </PropertyGroup>
+    <Target Name="Compile" />
+    <Target Name="Build" />
+    <Target Name="SchemaMigration" BeforeTargets="BeforeBuild">
+        <Message Importance="High" Text="Installing schema generator tool" />
+        <Exec Command="dotnet tool restore" />
+        <Message Importance="High" Text="Generating migration schemas..." />
+        <Exec Command="dotnet tool run ModernUOSchemaGenerator '$(ProjectDir)..\..\ModernUO.sln'" />
+    </Target>
+</Project>