feat: Source generated Serialization/Deserialization (#550)

### Features
* Fully abstracts serialization by using compile-time attributes.
* Supports serializing the following:
  - Primitives (integers, strings, etc)
  - IP Addresses
  - BigDecimal
  - DateTime, Delta DateTimes
  - TimeSpan
  - Server.Race
  - Server.Map
  - Point2D, Point3D, Rect2D, Rect3D
  - Existing/New `ISerializable` references
  - Lists/Sets of serializable types
  - Type with a `Serialize` method and constructor that takes an `IGenericReader`
* Supports forward-only migration
* Supports existing RunUO deserialization for older versions by changing to the following signature:
  - `public void OldDeserialize(IGenericReader reader, int version)`
  - Must remove deserializing the version since this is already done
* Supports serializing from private fields or custom made properties.
* Types do not require inheriting Item/Mobile. Code gen will fully create `ISerializable` information.
  - This is not recommended yet, since it requires wiring to `Persistence` which will cause lots of unresolved symbol errors until code gen is built.

### Example
```cs
using System.Collections.Generic;

namespace Server.Items
{
    [Serializable(1)]
    public partial class TestItem1 : Item
    {
        [SerializableField(1)]
        [SerializableFieldAttr("[CommandProperty(AccessLevel.Administrator)]")]
        private List<Item> _someProperty;

        private void Deserialize(IGenericReader reader, int version)
        {
        }
    }
}
```

Generates this:
```cs
namespace Server.Items
{
    public partial class TestItem1
    {
#pragma warning disable 0414
        private const int _version = 1;
#pragma warning restore 0414

        [CommandProperty(AccessLevel.Administrator)]
        public System.Collections.Generic.List<Server.Item> SomeProperty
        {
            get => _someProperty;
            set
            {
                if (value != _someProperty)
                {
                    ((ISerializable)this).MarkDirty();
                    _someProperty = value;
                }
            }
        }

        public TestItem1(Serial serial) : base(serial)
        {
        }

        public override void Serialize(IGenericWriter writer)
        {
            var savePosition = ((Server.ISerializable)this).SavePosition;
            if (savePosition > -1)
            {
                writer.Seek(savePosition, System.IO.SeekOrigin.Begin);
                return;
            }
            writer.WriteEncodedInt(_version);
            writer.Write(_someProperty);
        }

        public override void Deserialize(IGenericReader reader)
        {
            var version = reader.ReadEncodedInt();
            if (version < 1)
            {
                OldDeserialize(reader, version);
                ((Server.ISerializable)this).MarkDirty();
                return;
            }
            SomeProperty = reader.ReadEntityList<Server.Item>();
        }
    }
}
```

And this:
```json
{
  "version": 1,
  "type": "TestItem1",
  "properties": [
    {
      "name": "SomeProperty",
      "type": "System.Collections.Generic.List\u003CServer.Item\u003E",
      "rule": "ListMigrationRule",
      "ruleArguments": [
        "Server.Item",
        "SerializableInterfaceMigrationRule"
      ]
    }
  ]
}
```

Projects/SerializationGenerator/SerializerSyntaxReceiver.cs

@@ -0,0 +1,48 @@
+/*************************************************************************
+ * ModernUO                                                              *
+ * Copyright (C) 2019-2021 - ModernUO Development Team                   *
+ * Email: hi@modernuo.com                                                *
+ * File: SyntaxReceiver.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.Collections.Generic;
+using System.Linq;
+using Microsoft.CodeAnalysis;
+using Microsoft.CodeAnalysis.CSharp.Syntax;
+
+namespace SerializationGenerator
+{
+    public class SerializerSyntaxReceiver : ISyntaxContextReceiver
+    {
+        public List<IFieldSymbol> Fields { get; } = new();
+
+        public static HashSet<string> AttributeTypes { get; } = new();
+
+        public void OnVisitSyntaxNode(GeneratorSyntaxContext context)
+        {
+            if (context.Node is FieldDeclarationSyntax { AttributeLists: { Count: > 0 } } fieldDeclarationSyntax)
+            {
+                foreach (VariableDeclaratorSyntax variable in fieldDeclarationSyntax.Declaration.Variables)
+                {
+                    if (context.SemanticModel.GetDeclaredSymbol(variable) is not IFieldSymbol fieldSymbol)
+                    {
+                        return;
+                    }
+
+                    if (fieldSymbol.GetAttributes().Any(ad => AttributeTypes.Contains(ad.AttributeClass?.ToDisplayString())))
+                    {
+                        Fields.Add(fieldSymbol);
+                    }
+                }
+            }
+        }
+    }
+}